@article {1563426, title = {Benthic pterobranchs from the Cambrian (Drumian) Marjum Konservat-Lagerstatte of Utah}, journal = {Papers in Palaeontology }, year = {In Press}, author = {R. Lerosey-Aubril and J. Maletz and R. Coleman and L. Del Mouro and R. R. Gaines and J. Skabelund and J. Ortega-Hern{\'a}ndez} } @article {1557176, title = {The Fezouata Shale Formation biota is typical for the high latitudes of the early Ordovician {\textendash} a quantitative approach}, journal = {Paleobiology}, year = {In Press}, author = {J. C. Richards and K. Nanglu and J. Ortega-Hern{\'a}ndez} } @article {1518571, title = {Stuck in the mud: experimental taphonomy and computed tomography demonstrate the critical role of sediment in three-dimensional carcass stabilization during early fossil diagenesis}, journal = {Research Square}, year = {Forthcoming}, abstract = {

Exceptionally preserved fossils provide critical information on the morphology and ecology of extinct organisms, but their formation remains poorly understood. Experimental taphonomy has produced critical insights that allow us to better understand preservation biases, but they typically do not reflect realistic depositional environments, employ destructive sampling, and are restricted to a two-dimensional setting. Here, we utilize micro-computed tomography to non-invasively visualize the process of decay of carcasses of the branchiopod Triops longicaudatus for a year of post-burial decay. The earliest stages of post-burial diagenesis are dynamic and produce marked differences in relative density within each of the experimental replicates affecting both the carcass and the surrounding sediment. After 64 weeks, specimens are still detectable as three-dimensional voids that capture the body in life position and external morphological features. Sediment plays a critical role in carcass stabilization and the resulting voids provide sites for mineral precipitation needed for exceptional three-dimensional fossilization.

}, url = {https://www.researchsquare.com/article/rs-3192621/v1}, author = {M. Waskom and S. R. Losso and J. Ortega-Hern{\'a}ndez} } @article {1562096, title = {Post-Cambrian survival of the tubicolous scalidophoran Selkirkia}, journal = {Biology Letters}, volume = {20}, year = {2024}, pages = {20240042}, abstract = {

Scalidophoran worms represent common infaunal components of early and middle Cambrian Burgess Shale-type fossil biotas. Early scalidophorans resemble extant priapulids based on overall morphology, but the genus Selkirkia represents the earliest record of tube dwelling for the group. Despite its ubiquitous presence in exceptional marine deposits, whether the exclusively Cambrian occurrence of Selkirkia reflects its entire evolutionary history or is affected by taphonomic biases remains unresolved. Here, we demonstrate the post-Cambrian survival of Selkirkia based on new material from the Lower Ordovician Fezouata Shale biota of Morocco. The discovery of Selkirkia in the Fezouata Shale extends the biostratigraphic range of the genus by 25 million years and its palaeobiogeographic occurrence to the high latitudes of Gondwana, strengthens the evolutionary links between Cambrian and Ordovician Burgess Shale-type biotas and increases scalidophoran diversity for the Fezouata Shale biota otherwise consisting exclusively of the palaeoscolecid Palaeoscolex? tenensis. The tube of Selkirkia underwent negligible external change for over 40 million years, indicating a high degree of morphological stasis during the Early Palaeozoic. A tubicolous mode of life is rare among extant priapulids and expressed only in Maccabeus, which forms a delicate tube from agglutinated plant debris, unlike the macroscopic secreted cuticular tube of Selkirkia.

}, url = {https://royalsocietypublishing.org/doi/10.1098/rsbl.2024.0042}, author = {K. Nanglu and J. Ortega-Hern{\'a}ndez} } @article {1543451, title = {Convergent adaptation of true crabs (Decapoda, Brachyura) to a gradient of terrestrial environments}, journal = {Systematic Biology }, year = {2023}, url = {https://academic.oup.com/sysbio/advance-article/doi/10.1093/sysbio/syad066/7370615}, author = {J.M. Wolfe and L. Ballou and J. Luque and V. Watson-Zink and S.T. Ahyong and J. Barido-Sottani and T.Y. Chan and K.A. Crandall and S.R. Daniels and D.L. Felder and H. Mancke and J.W. Martin and P.K.L. Ng and J. Ortega-Hern{\'a}ndez and E. Palacios Theil and N.D. Pentcheff and R. Robles and B.P. Thoma and L.M. Tsang and R. Wetzer and A.M. Windsor and H.D. Bracken-Grissom} } @article {1538036, title = {Convergent evolution of ventral adaptations for enrollment in trilobites and extant euarthropods}, journal = {Proceedings of the Royal Society B}, volume = {290}, year = {2023}, pages = {20232212}, abstract = {

The ability to enrol for protection is an effective defensive strategy that has convergently evolved multiple times in disparate animal groups ranging from euarthropods to mammals. Enrolment is a staple habit of trilobites, and their biomineralized dorsal exoskeleton offered a versatile substrate for the evolution of interlocking devices. However, it is unknown whether trilobites also featured ventral adaptations for enrolment. Here, we report ventral exoskeletal adaptations that facilitate enrolment in exceptionally preserved trilobites from the Middle Ordovician Walcott{\textendash}Rust Quarry in New York State, USA. Walcott{\textendash}Rust trilobites reveal the intricate three-dimensional organization of the non-biomineralized ventral anatomy preserved as calcite casts, including the spatial relationship between the articulated sternites (i.e. ventral exoskeletal plates) and the wedge-shaped protopodites. Enrolment in trilobites is achieved by ventrally dipping the anterior margin of the sternites during trunk flexure, facilitated by the presence of flexible membranes, and with the close coupling of the wedge-shaped protopodites. Comparisons with the ventral morphology of extant glomerid millipedes and terrestrial isopods reveal similar mechanisms used for enrolment. The wedge-shaped protopodites of trilobites closely resemble the gnathobasic coxa/protopodite of extant horseshoe crabs. We propose that the trilobites{\textquoteright} wedge-shaped protopodite simultaneously facilitated tight enrolment and gnathobasic feeding with the trunk appendages.

}, url = {https://www.biorxiv.org/content/10.1101/2023.09.28.560020v1}, author = {S.R. Losso and P. Affatato and K. Nanglu and J. Ortega-Hern{\'a}ndez} } @article {1507326, title = {A mid-Cambrian tunicate and the deep origin of the ascidiacean body plan}, journal = {Nature Communications}, volume = {14}, year = {2023}, pages = {3832}, abstract = {

Tunicates are an evolutionarily significant subphylum of marine chordates, with their phylogenetic position as the sister-group to Vertebrata making them key to unraveling our own deep time origin. Tunicates greatly vary with regards to morphology, ecology, and life cycle, but little is known about the early evolution of the group, e.g. whether their last common ancestor lived freely in the water column or attached to the seafloor. Additionally, tunicates have a poor fossil record, which includes only one taxon with preserved soft-tissues. Here we describe Megasiphon thylakos nov., a 500-million-year-old tunicate from the Marjum Formation\ of Utah, which features a barrel-shaped body with two long siphons and prominent longitudinal muscles. The ascidiacean-like body of this new species suggests two alternative hypotheses for early tunicate evolution. The most likely scenario posits M. thylakos belongs to stem-group Tunicata, suggesting that a biphasic life cycle, with a planktonic larva and a sessile epibenthic adult, is ancestral for this entire subphylum. Alternatively, a position within the crown-group indicates that the divergence between appendicularians and all other tunicates occurred 50 million years earlier than currently estimated\ based on molecular clocks. Ultimately, M. thylakos demonstrates that fundamental components of the modern tunicate body plan were already established shortly after the Cambrian Explosion.

}, url = {https://www.nature.com/articles/s41467-023-39012-4}, author = {Nanglu, K. and Lerosey-Aubril, R. and Weaver, J. C. and Ortega-Hernandez, J.} } @article {1532216, title = {Organic walled microfossils in wet peperites from the early Cretaceous Paran{\'a}-Etendeka volcanism of Brazil}, journal = {Scientific Reports}, volume = {13}, year = {2023}, pages = {15362 }, abstract = {

Large igneous provinces (LIPs) are major magmatic events that have a significant impact on the global environment and the biosphere, for example as triggers of mass extinctions. LIPs provide an excellent sedimentological and geochemical record of short but intense periods of geological activity in the past, but their contribution towards understanding ancient life is much more restricted due to the destructive nature of their igneous origin. Here, we provide the first paleontological evidence for organic walled microfossils extracted from wet peperites from the Early Cretaceous Paran{\'a}-Etendeka intertrappean deposits of the Paran{\'a} basin in Brazil. Wet peperites are a volcaniclastic rock formed by the interaction of lava and subaqueous sediments.The Paran{\'a}-Etendeka was formed during the Valanginian (ca. 132\ Ma) as a continental flood basalt in present day South America and Namibia, and released enormous amounts of carbon dioxide, sulfur dioxide, methane and hydrogen fluoride into the atmosphere. The organic walled microfossils recovered from the Paran{\'a}-Etendeka peperites include pollen grains, spores, acritarchs, and other remains of unidentifiable organic matter. In addition to the peperites, organic walled microfossils were also found in heterolithic sandstones and interpillow sandstones. Our findings represent the first insight into the biodiversity of the Paran{\'a} Basin during the Early Cretaceous during a period of intense magmatism, and the microfossil assemblages corroborate a regional paleoclimatic transition from arid to more humid conditions that were likely induced by the volcanic activity. We corroborate the potential of wet peperite rocks as a valuable source of paleobiological data and emphasize the importance of sampling volcaniclastic units that have been traditionally considered with lower fossiliferous potential due to their igneous origin.

}, url = {https://www.nature.com/articles/s41598-023-42483-6}, author = {L. Del Mouro and B. Becker-Kerber and V. A. Janasi and de Araujo-Carvalho and B. L. Waichel and E. F. Lima and L. M. M. Rossetti and V. Cruz and M. Souza-Silva and N. Famelli and J. Ortega-Hern{\'a}ndez} } @article {1521311, title = {Rhabdopleurid epibionts from the Ordovician Fezouata Shale biota and the longevity of cross-phylum interactions}, journal = {Communications Biology}, volume = {2}, year = {2023}, abstract = {

Evidence of interspecific interactions in the fossil record is rare but offers valuable insights into ancient ecologies. Exceptional fossiliferous sites can preserve complex ecological interactions involving non-biomineralized organisms, but most of these examples are restricted to Cambrian Lagerst{\"a}tten. Here we report an exceptionally preserved cross-phylum interspecific interaction from the Tremadocian-aged Lower Fezouata Shale Formation of Morocco, which consists of the phragmocone of an orthocone cephalopod that has been extensively populated post-mortem by tubicolous epibionts. Well-preserved transverse bands in a zig-zag pattern and crenulations along the margin of the unbranched tubes indicate that they correspond to pterobranch hemichordates, with a close morphological similarity to rhabdopleurids based on the bush-like growth of the dense tubarium. The discovery of rhabdopleurid epibionts in the Fezouata Shale highlights the paucity of benthic graptolites, which also includes the rooted dendroids Didymograptus and Dictyonema, relative to the substantially more diverse and abundant planktic forms known from this biota. We propose that the rarity of Paleozoic rhabdopleurid epibionts is likely a consequence of their ecological requirement for hard substrates for initial settlement and growth. The Fezouata rhabdopleurid also reveals a 480-million-year-old association of pterobranchs as epibionts of molluscs that persist to the present day.

}, url = {https://www.nature.com/articles/s42003-023-05377-x?utm_source=rct_congratemailt\&utm_medium=email\&utm_campaign=oa_20231011\&utm_content=10.1038/s42003-023-05377-x}, author = {K. Nanglu and M. E. Waskom and J. C. Richards and J. Ortega-Hern{\'a}ndez} } @article {1518841, title = {Taphonomy of non-biomineralized trilobite tissues preserved as calcite casts from the Ordovician Walcott-Rust Quarry, USA}, journal = {Communications Earth \& Environment}, volume = {4}, year = {2023}, pages = {330}, abstract = {Trilobites with appendages from the Rust Formation of New York State were discovered in the 1870s and represent one of the earliest known cases of exceptional preservation of non-biomineralized tissues. The Rust Formation trilobites feature three-dimensionally preserved walking legs and delicate respiratory lamellae, but the mechanism behind their fossilization remains unknown. Here we show that after burial, carcass decay produced framboidal pyrite, while fibrous calcite precipitated on the visceral side of the body, followed by the widespread formation of sparry calcite crystal replicating non-biomineralized morphological features. Trilobites and co-occurring calcite veins show no chemical or petrographic differences, rejecting the hypothesis that exceptional preservation was caused by a local microenvironment within enrolled trilobites. These results suggest that fine-grained sediment provided support for the appendages and facilitated their fossilization through calcite replacement. Our findings carry broader implications for understanding the exceptional three-dimensional preservation of animal Paleozoic body fossils through calcite casts.}, url = {https://www.nature.com/articles/s43247-023-00981-5.epdf?sharing_token=RVxWW8Ci7gRE2fttWRq3ltRgN0jAjWel9jnR3ZoTv0PICBviaxbcHMyuY31unKPvCZIlhJD0AqvhNfU7RsHIGmJURYzmDi1_dekzjpcol3b_zmpDx2IXH7pgH5ZUm19EjfBslgCkRJT_e3yyAk5jdiLskXXsoqPg2XTSnNaFhPI\%3D}, author = {S. R. Losso and J. Thines and J. Ortega-Hern{\'a}ndez} } @article {1414975, title = {Three-dimensional morphology of the biramous appendages in Isoxys from the early Cambrian of South China, and its implications for early euarthropod evolution}, journal = {Proceedings of the Royal Society B}, volume = {290}, year = {2023}, pages = {20230335 }, abstract = {

Early euarthropod evolution involved a major transition from lobopodian-like taxa to organisms featuring a segmented, well-sclerotized trunk (arthrodization) and limbs (arthropodization). However, the precise origin of a completely arthrodized trunk and arthropodized ventral biramous appendages remain controversial, as well as the early onset of anterior{\textendash}posterior limb differentiation in stem-group euarthropods. New fossil material and micro-computed tomography inform the detailed morphology of the arthropodized biramous appendages in the carapace-bearing euarthropod Isoxys curvirostratus from the early Cambrian Chengjiang biota. In addition to well-developed grasping frontal appendages, I. curvirostratus possesses two batches of morphologically and functionally distinct biramous limbs. The first batch consists of four pairs of short cephalic appendages with robust endites with a feeding function, whereas the second batch has more elongate trunk appendages for locomotion. Critically, our new material shows that the trunk of I. curvirostratus was not arthrodized. The results of our phylogenetic analyses recover isoxyids as some of the earliest branching sclerotized euarthropods, and strengthens the hypothesis that arthropodized biramous appendages evolved before full body arthrodization.

}, url = {https://royalsocietypublishing.org/doi/10.1098/rspb.2023.0335}, author = {C. Zhang and Liu, Y. and J. Ortega-Hern{\'a}ndez and Wolfe, J. M. and C. Jin and H. Mai and X. G. Hou and J. Guo and D. Zhai} } @article {1405671, title = {Before trilobite legs: Pygmaclypeatus daziensis reconsidered and the ancestral appendicular organization of Cambrian artiopods}, journal = {Philosophical Transactions of the Royal Society B }, volume = {377 }, year = {2022}, pages = {20210030}, abstract = {

The Cambrian Stage 3 Chengjiang biota in South China is one of the most influential Konservat Lagerstatten worldwide thanks to the fossilization of diverse nonbiomineralizing organisms through pyritization. Despite their contributions to understanding the evolution of early animals, several Chengjiang species remain poorly known due to their scarcity and/or incomplete preservation. Here, we use micro-computed tomography to reveal in detail the ventral appendage organization of the enigmatic non-trilobite artiopod Pygmaclypeatus daziensis, one of the rarest euarthropods in Chengjiang, and explore its functional ecology and broader evolutionary significance. P. daziensis possesses a set of uniramous antennae and 14 pairs of post-antennal biramous appendages, the latter of which show an unexpectedly high degree of heteronomy based on the localized differentiation of the protopodite, endopod and exopod along the antero-posterior body axis. The small body size (less than 2 cm), presence of delicate spinose endites, and well-developed exopods with multiple paddle-shaped lamellae on the appendages of P. daziensis indicate a nekto-benthic mode of life, and a scavenging/detritus feeding strategy. P. daziensis shows that appendage heteronomy is phylogenetically widespread within Artiopoda, the megadiverse clade that includes trilobites and their relatives with nonbiomineralizing exoskeletons and suggests that a single exopod lobe with paddle like lamellae is ancestral for this clade.

}, url = {https://royalsocietypublishing.org/doi/10.1098/rstb.2021.0030}, author = {Schmidt, M. and X. G. Hou and J. Belojevic and D. Zhai and J. Mai and R. R. Melzer and J. Ortega-Hern{\'a}ndez and Liu, Y.} } @article {1425422, title = {Biomineralization: integrating mechanism and evolutionary history}, journal = {Science Advances}, volume = {8}, year = {2022}, pages = {eabl9653 }, abstract = {
Calcium carbonate (CaCO3) biomineralizing organisms have played major roles in the history of life and the global carbon cycle during the past 541 Ma. Both marine diversification and mass extinctions reflect physiological responses to environmental changes through time. An integrated understanding of carbonate biomineralization is necessary to illuminate this evolutionary record and to understand how modern organisms will respond to 21st century global change. Biomineralization evolved independently but convergently across phyla, suggesting a unity of mechanism that transcends biological differences. In this review, we combine CaCO3 skeleton formation mechanisms with constraints from evolutionary history, omics, and a meta-analysis of isotopic data to develop a plausible model for CaCO3 biomineralization applicable to all phyla. The model provides a framework for understanding the environmental sensitivity of marine calcifiers, past mass extinctions, and resilience in 21st century acidifying oceans. Thus, it frames questions about the past, present, and future of CaCO3 biomineralizing organisms.
}, url = {https://www.science.org/doi/10.1126/sciadv.abl9653}, author = {P. Gilbert and Bergmann, K. D. and N. Boekelheide and S. Tambutte and T. Mass and F. Marin and J.F. Adkins and J. Erez and B. Gilbert and V. Knutson and M. Cantine and J. Ortega-Hern{\'a}ndez and A.H, Knoll} } @article {1430896, title = {Claspers in the mid-Cambrian Olenoides serratus indicate horseshoe crab-like mating in trilobites}, journal = {Geology}, volume = {50}, year = {2022}, pages = {897-901}, abstract = {

Sexual reproduction represents a fundamental aspect of animal biology, but the diversity of reproductive strategies among early Paleozoic metazoans remains obscure. Direct evidence of reproductive strategies comes from exceptionally preserved egg masses in Cambrian and Ordovician euarthropods such as waptiids and trilobites, but anatomical or behavioral adaptations for mating in these taxa are all but unknown. We demonstrate the presence of functionally specialized appendages in the mid-Cambrian (Wuliuan) Burgess Shale trilobite Olenoides serratus. New material of O. serratus preserves significantly modified and reduced endopodites underneath the seventh thoracic and first pygidial tergites. Comparison with extant euarthropods indicates that these specialized limbs are functional analogs to claspers, which are used by sexually mature males to grasp females prior to or during mating. The claspers in O. serratus were most likely used by the male to hold onto the posterior pygidial spines of the female during amplex, similar to the strategy observed in the horseshoe crab Limulus polyphemus. The new appendicular data from O. serratus provide the first direct evidence for trilobite sexual dimorphism based on the non-biomineralized ventral anatomy. Our findings illuminate the reproductive biology of trilobites and indicate that complex mating behaviors observed in extant euarthropods originated during the Cambrian explosion.

}, url = {https://pubs.geoscienceworld.org/gsa/geology/article/50/8/897/613523/Claspers-in-the-mid-Cambrian-Olenoides-serratus}, author = {S.R. Losso and J. Ortega-Hern{\'a}ndez} } @article {1424099, title = {Neuroanatomy in a middle Cambrian mollisoniid and the ancestral nervous system organization of chelicerates}, journal = {Nature Communications}, volume = {13}, year = {2022}, abstract = {

Recent years have witnessed a steady increase in reports of fossilized nervous tissues among Cambrian total-group euarthropods, which allow reconstructing the early evolutionary history of these animals. Here, we describe the central nervous system of the stem-group chelicerate Mollisonia symmetrica from the mid-Cambrian Burgess Shale. The fossilized neurological anatomy of M. symmetrica includes optic nerves connected to a pair of lateral eyes, a putative condensed cephalic synganglion, and a metameric ventral nerve cord. Each trunk tergite is associated with a condensed ganglion bearing lateral segmental nerves, and linked by longitudinal connectives. The nervous system is preserved as reflective carbonaceous films underneath the phosphatized digestive tract. Our results suggest that M. symmetrica illustrates the ancestral organization of stem-group Chelicerata before the evolution of the derived neuroanatomical characters observed in Cambrian megacheirans and extant representatives. Our findings reveal a conflict between the phylogenetic signals provided by neuroanatomical and appendicular data, which we interpret as evidence of mosaic evolution in the chelicerate stem-lineage.

}, url = {https://www.nature.com/articles/s41467-022-28054-9}, author = {J. Ortega-Hern{\'a}ndez and Lerosey-Aubril, R. and S.R. Losso and J. C. Weaver} } @article {1425720, title = {New fossil assemblages from the Early Ordovician Fezouata Biota}, journal = {Scientific Reports}, volume = {12}, year = {2022}, pages = {20773}, abstract = {

The Fezouata Biota (Morocco) is a unique Early Ordovician fossil assemblage. The discovery of this biota revolutionized our understanding of Earth{\textquoteright}s early animal diversifications{\textemdash}the Cambrian Explosion and the Ordovician Radiation{\textemdash}by suggesting an evolutionary continuum between both events. Herein, we describe Taichoute, a new fossil locality from the Fezouata Shale. This locality extends the temporal distribution of fossil preservation from this formation into the upper Floian, while also expanding the range of depositional environments to more distal parts of the shelf. In Taichoute, most animals were transported by density flows, unlike the in-situ preservation of animals recovered in previously investigated Fezouata sites. Taichoute is dominated by three-dimensionally preserved, and heavily sclerotized fragments of large euarthropods{\textemdash}possibly representing nektobenthic/nektic bivalved taxa and/or hurdiid radiodonts. Resolving whether this dominance reflects a legitimate aspect of the original ecosystem or a preservational bias requires an in-depth assessment of the environmental conditions at this site. Nevertheless, Taichoute provides novel preservational and palaeontological insights during a key evolutionary transition in the history of life on Earth.

}, url = {https://www.nature.com/articles/s41598-022-25000-z}, author = {F. Saleh and R. Vaucher and M. Vidal and El Hariri, K. and L. Laibl and Daley, A.C. and J. C. Gutierrez-Marco and Y. Candela and D. Harper and J. Ortega-Hern{\'a}ndez and Ma, X. and A. Rida and D. Vizcaino and V. Lefebvre} } @article {1432113, title = {A new lobopodian from the middle Cambrian of Utah: did swimming body flaps convergently evolve in stem-group arthropods?}, journal = {Papers in Palaeontology}, volume = {8}, year = {2022}, pages = {e1450}, abstract = {

Arthropods are ubiquitous in all modern habitats and yet their origin remains poorly documented. It is widely thought that their segmented and arthrodized body evolved from the annulated vermiform body of a lobopodian ancestor c. 540 Ma. This major transformation included the evolution of sclerotized and articulated appendages from annulated non-jointed limbs or lobopods. However, this scenario is complicated by the presence in many stem-group arthropods of body flaps of various origins, characteristics and functions. We describe the new lobopodian Utahnax vannieri gen. et sp. nov. from Drumian strata of the House Range in Utah. Known from an incomplete specimen, this taxon features a vermiform, annulated body flanked by pairs of swimming flaps, except in the caudal region, and a digestive system with putative glands. Extensions of the body cavity into the body flaps of Utahnax suggest that they are modified lobopods similar to the ventral body flaps of radiodonts; as such, they are not homologous to the dorsal body flaps of the stem-group arthropods Opabinia, Pambdelurion, and possibly Kerygmachela. We discuss the details of the limb anatomy of these three taxa and consider an alternative interpretation for Kerygmachela. Despite morphological similarities in radiodonts, Utahnax, and possibly Kerygmachela, our parsimony and Bayesian inference phylogenetic analyses suggest that ventral body flaps have evolved convergently in those taxa, probably accompanying a shift towards a predominantly swimming predatory lifestyle. Ecological competition with radiodonts is proposed as an explanation for the scarcity of non-radiodont swimming lobopodians in Cambrian Lagerst{\"a}tten.

}, url = {https://onlinelibrary.wiley.com/doi/full/10.1002/spp2.1450}, author = {Lerosey-Aubril, R. and J. Ortega-Hern{\'a}ndez} } @article {1393824, title = {New opabiniid diversifies the weirdest wonders of the euarthropod lower stem group}, journal = {Proceedings of the Royal Society B}, volume = {289}, year = {2022}, pages = {20212093}, abstract = {

Once considered "weird wonders" of the Cambrian, the emblematic Burgess Shale animals Anomalocaris and Opabinia are now recognized as lower stem-group euarthropods. Anomalocaris and its relatives (radiodonts) had a worldwide distribution and survived until at least the Devonian, whereas - despite intense study - Opabinia remains the only formally described opabiniid to date. Here we reinterpret a fossil from the Wheeler Formation of Utah as a new opabiniid, KUMIP 314087. By visualizing the sample of phylogenetic topologies in treespace, our results fortify support for the position of KUMIP 314087 beyond the nodal support traditionally applied. Our phylogenetic evidence expands opabiniids to multiple Cambrian Stages spanning approximately five million years. Our results underscore the power of treespace visualization for resolving imperfectly preserved fossils and expanding the known diversity and spatiotemporal ranges within the euarthropod lower stem group.

}, url = {https://royalsocietypublishing.org/doi/10.1098/rspb.2021.2093}, author = {Pates, S. and Wolfe, J. M. and Lerosey-Aubril, R. and Daley, A.C. and J. Ortega-Hern{\'a}ndez} } @article {1441354, title = {Ventral morphology of the non-trilobite artiopod Retifacies abnormalis Hou, Chen \& Lu, 1989, from the early Cambrian Chengjiang biota, China}, journal = {Biology}, volume = {11}, year = {2022}, pages = {1235}, abstract = {
The artiopodans represent a diverse group of euarthropods with a typically flattened dorsal exoskeleton that covers numerous pairs of biramous ventral appendages, and which are ubiquitous faunal components of the 518-million-year-old Chengjiang Lagerst{\"a}tte in South China. Despite their abundance, several Chengjiang artiopodans remain poorly known, such as the large euarthropoda Retifacies abnormalis, Hou, Chen \& Lu, 1989, which is distinguished by the presence of mesh-like ornamentation on its dorsal exoskeleton. Although only a few ventral details were described in a single study in 25 years, it has been frequently featured in phylogenetic analyses that explore the relationships between Cambrian euarthropods. Here, we employ micro-CT and fluorescent microphotography to investigate the exceptionally preserved ventral morphology of R. abnormalis and explore its phylogenetic implications through maximum parsimony and Bayesian inference. Detailed morphology revealed here better supports R. abnormalis as a sister group to the diminutive artiopod Pygmaclypeatus daziensis, also known from Chengjiang, and strengthens the close relationship of these taxa that have been suggested by previous studies as early-branching representatives of Trilobitomorpha. Cephalic appendages suggest this animal might be a scavenger, possibly feeding on soft-bodied organisms. Different pairs of pygidial appendages suggest an anamorphic post-embryonic ontogeny, which adds to the understanding of the developmental mode of Cambrian artiopods, and further supports the statement that post-hatching segment addition occurred in the ancestor of Euarthropoda. View Full-Text
}, url = {https://www.mdpi.com/2079-7737/11/8/1235}, author = {M. Zhang and Liu, Y. and X. G. Hou and J. Ortega-Hern{\'a}ndez and H. Mai and Schmidt, M. and R. R. Melzer and J. Guo} } @article {1441609, title = {Ventral organisation of Jianfengia multisegmentalis Hou, and its implications for the head segmentation of megacheirans}, journal = {Palaeontology}, volume = {e12624 }, year = {2022}, abstract = {

Megacheirans, or great-appendage euarthropods, have featured prominently in discussions regarding the early evolution of the head region in total-group Euarthropoda. However, several aspects of the ventral morphology of most representatives remain incompletely known given the loss of data associated with fossil compression, coupled with the rarity of some of these taxa. Here, we describe the ventral aspect of head organization of the jianfengiid megacheiran Jianfengia multisegmentalis using micro computed-tomography, and explore its evolutionary significance. The head consists of a pair of stalked eyes, a pair of great appendages, and four pairs of biramous appendages, all covered by a dorsal head shield. The rostral portion of the head bears a median projection, which we interpret as an anterior sclerite akin to that observed in several other Cambrian euarthropods. The anterior sclerite in J. multisegmentalis articulates with robust stalks with rounded projections in a more adaxial position, and bears the compound eyes. Critically, the ventral side of the head of J. multisegmentalis features a prominent lobe-shaped hypostome/labrum complex located immediately behind the great appendages, and between the first pair of biramous appendages. This situation is consistent with that observed in Leanchoilia illecebrosa and suggests a conserved, and possibly ancestral, pattern of a six-segmented head (eyes, great appendages and four biramous limb appendages) with a hypostome/labrum complex for Megacheira. The existence of the hypostome/labrum complex in J. multisegmentalis falsifies the hypothesis that the anterior projections on the head of jianfengiids might be homologues of the euarthropod labrum.

}, url = {https://onlinelibrary.wiley.com/doi/full/10.1111/pala.12624}, author = {X. Zhang and Liu, Y. and R. J. O{\textquoteright}Flynn and Schmidt, M. and R. R. Melzer and Hou, X. and H. Mai and J. Guo and J. Ortega-Hern{\'a}ndez} } @article {1418442, title = {Oh, my Cambrian nerves}, journal = {Current Biology}, volume = {31}, year = {2021}, pages = {R1132-R1135}, abstract = {

Developmental gene expression suggests a cryptic subdivision of the anterior brain in euarthropods. A new study illustrates delicate details of the nervous system from exceptionally preserved 500-million-year-old Chinese fossils, supporting the bipartite origin of the anterior brain among Cambrian representatives.

}, url = {https://www.sciencedirect.com/science/article/pii/S096098222101201X}, author = {Wolfe, J. M. and J. Ortega-Hern{\'a}ndez} } @article {1383458, title = {Biomechanical analysis of Cambrian euarthropods limbs reveal their effectiveness in mastication and durophagy}, journal = {Proceedings of the Royal Society B }, volume = {20202075 }, year = {2021}, abstract = {

Durophagy arose in the Cambrian and greatly influenced the diversification of biomineralized defensive structures throughout the Phanerozoic. Spinose gnathobases on protopodites of Cambrian euarthropod limbs are considered key innovations for shell-crushing, yet few studies have demonstrated their effectiveness with biomechanical models. Here we present finite-element analysis models of two Cambrian trilobites with prominent gnathobases{\textemdash}Redlichia rex and Olenoides serratus{\textemdash}and compare these to the protopodites of the Cambrian euarthropod Sidneyia inexpectans and the modern American horseshoe crab, Limulus polyphemus. Results show that L. polyphemus, S. inexpectans and R. rex have broadly similar microstrain patterns, reflecting effective durophagous abilities. Conversely, low microstrain values across the O. serratus protopodite suggest that the elongate gnathobasic spines transferred minimal strain, implying that this species was less well-adapted to masticate hard prey. These results confirm that Cambrian euarthropods with transversely elongate protopodites bearing short, robust gnathobasic spines were likely durophages. Comparatively, taxa with shorter protopodites armed with long spines, such as O. serratus, were more likely restricted to a soft food diet. The prevalence of Cambrian gnathobase-bearing euarthropods and their various feeding specializations may have accelerated the development of complex trophic relationships within early animal ecosystems, especially the {\textquoteleft}arms race{\textquoteright} between predators and biomineralized prey.

}, url = {https://royalsocietypublishing.org/doi/10.1098/rspb.2020.2075}, author = {R.D.C. Bicknell and J.D. Holmes and G.D. Edgecombe and S.R. Losso and J. Ortega-Hern{\'a}ndez and S. Wroe and J.R. Paterson} } @article {1410169, title = {Cambrian comb jellies from Utah illuminate the early evolution of nervous and sensory systems in ctenophores}, journal = {iScience}, volume = {24}, year = {2021}, pages = {102943}, abstract = {
Ctenophores are a group of predatory macroinvertebrates whose controversial phylogenetic position has prompted several competing hypotheses regarding the evolution of animal organ systems. Although ctenophores date back at least to the Cambrian, they have a poor fossil record due to their gelatinous bodies. Here, we describe two ctenophore species from the Cambrian of Utah, which illuminate the early evolution of nervous and sensory features in the phylum. Thalassostaphylos elegans has 16 comb rows, an oral skirt, and an apical organ with polar fields. Ctenorhabdotus campanelliformis has 24 comb rows, an oral skirt, an apical organ enclosed by a capsule and neurological tissues preserved as carbonaceous films. These are concentrated around the apical organ and ciliated furrows, which connect to a circumoral nerve ring via longitudinal axons. C. campanelliformis deviates from the neuroanatomy of living ctenophores and demonstrates a substantial complexity in the nervous system of Cambrian ctenophores.
}, url = {https://www.sciencedirect.com/science/article/pii/S2589004221009111$\#$!}, author = {L. A. Parry and Lerosey-Aubril, R. and J. C. Weaver and J. Ortega-Hern{\'a}ndez} } @article {1401873, title = {Central nervous system of a 310-million-year-old horseshoe crab: expanding the taphonomic window for nervous system preservation}, journal = {Geology}, volume = {49}, year = {2021}, pages = {1381-1385 }, abstract = {

The central nervous system (CNS) presents unique insight into the behaviors and ecology of extant and extinct animal groups. However, neurological tissues are delicate and prone to rapid decay, and thus their occurrence as fossils is mostly confined to Cambrian Burgess Shale{\textendash}type deposits and Cenozoic amber inclusions. We describe an exceptionally preserved CNS in the horseshoe crab Euproops danae from the late Carboniferous (Moscovian) Mazon Creek Konservat-Lagerst{\"a}tte in Illinois, USA. The E. danae CNS demonstrates that the general prosomal synganglion organization has remained essentially unchanged in horseshoe crabs for \>300 m.y., despite substantial morphological and ecological diversification in that time. Furthermore, it reveals that the euarthropod CNS can be preserved by molding in siderite and suggests that further examples may be present in the Mazon Creek fauna. This discovery fills a significant temporal gap in the fossil record of euarthropod CNSs and expands the taphonomic scope for preservation of detailed paleoneuroanatomical data in the Paleozoic to siderite concretion Lagerst{\"a}tten of marginal marine deposits.

}, url = {https://pubs.geoscienceworld.org/gsa/geology/article/doi/10.1130/G49193.1/606398/Central-nervous-system-of-a-310-m-y-old-horseshoe}, author = {R.D.C. Bicknell and J. Ortega-Hern{\'a}ndez and G.D. Edgecombe and R.R. Gaines and J.R. Paterson} } @article {1380845, title = {The diverse radiodont fauna from the Marjum Formation of Utah, USA (Cambrian: Drumian)}, journal = {PeerJ}, volume = {9}, year = {2021}, pages = {e10509 }, abstract = {

Radiodonts have long been known from Cambrian deposits preserving non-biomineralizing organisms. In Utah, the presence of these panarthropods in the Spence and Wheeler (House Range and Drum Mountains) biotas is now well-documented. Conversely, radiodont occurrences in the Marjum Formation have remained scarce. Despite the large amount of work undertaken on its diverse fauna, only one radiodont (Peytoia) has been reported from the Marjum Biota. In this contribution we quadruple the known radiodont diversity of the Marjum fauna, with the description of the youngest members of two genera, Caryosyntrips and Pahvantia, and that of a new taxon Buccaspinea cooperi gen. et sp. nov. This new taxon can be identified from its large oral cone bearing robust hooked teeth with one, two, or three cusps, and by the unique endite morphology and organisation of its frontal appendages. Appendages of at least 12 podomeres bear six recurved plate-like endites proximal to up to four spiniform distal endites. Pahvantia hastata specimens from the Marjum Formation are particularly large, but otherwise morphologically indistinguishable from the carapace elements of this species found in the Wheeler Formation. One of the two new Caryosyntrips specimens can be confidently assigned to C. camurus. The other bears the largest spines relative to appendage length recorded for this genus, and possesses endites of variable size and unequal spacing, making its taxonomic assignment uncertain. Caryosyntrips, Pahvantia, and Peytoia are all known from the underlying Wheeler Formation, whereas isolated appendages from the Spence Shale and the Wheeler Formation, previously assigned to Hurdia, are tentatively reidentified as Buccaspinea. Notably, none of these four genera occurs in the overlying Weeks Formation, providing supporting evidence of a faunal restructuring around the Drumian-Guzhangian boundary. The description of three additional nektonic taxa from the Marjum Formation further documents the higher relative proportion of free-swimming species in this biota compared to those of the Wheeler and Weeks Lagerst{\"a}tten. This could be related to a moderate deepening of the basin and/or changing regional ocean circulation at this time.

}, url = {https://peerj.com/articles/10509/}, author = {Pates, S. and Lerosey-Aubril, R. and Daley, A.C. and Kier, C. and Bonino, E. and J. Ortega-Hern{\'a}ndez} } @article {1389882, title = {The endemic radiodonts of the Cambrian Stage 4 Guanshan Biota of South China}, journal = {Acta Palaeontologica Polonica}, volume = {66}, year = {2021}, pages = {255-274}, abstract = {

The Guanshan Biota (South China, Cambrian, Stage 4) contains a diverse assemblage of biomineralizing and non-biomineralizing animals. Sitting temporally between the Stage 3 Chengjiang and Wuliuan Kaili Biotas, the Guanshan Biota contains numerous fossil organisms that are exclusive to this exceptional deposit. The Guanshan Konservat-Lagerst{\"a}tte is also unusual amongst Cambrian strata that preserve non-biomineralized material, as it was deposited in a relatively shallow water setting. In this contribution we double the diversity of radiodonts known from the Guanshan Biota from two to four, and describe the second species of Paranomalocaris. In addition, we report the first tamisiocaridid from South China, and confirm the presence of a tetraradial oral cone bearing small and large plates in {\textquotedblleft}Anomalocaris{\textquotedblright} kunmingensis, the most abundant radiodont from the deposit. All four radiodont species, and three genera, are apparently endemic to the Guanshan Biota. When considered in the wider context of geographically and temporally comparable radiodont faunas, endemism in Guanshan radiodonts is most likely a consequence of the shallower and more proximal environment in which they lived. The strong coupling of free-swimming radiodonts and benthic communities underlines the complex relationship between the palaeobiogeographic and environmental distributions of prey and predators. This local adaptation of radiodonts to their prey is highlighted by the frontal appendage morphology of the two species of Paranomalocaris, apparently specialised to different feeding modes, while the recognition of the limited geographic range of some radiodont faunas highlights the importance of exploring as many deposits as possible to fully understand this group.

}, url = {http://www.app.pan.pl/article/item/app008702020.html}, author = {D.G. Jiao and Pates, S. and Lerosey-Aubril, R. and J. Ortega-Hern{\'a}ndez and Yang, J. and Lan, T. and Zhang, X. G.} } @article {1405361, title = {Furongian (Jiangshanian) occurrences of radiodonts in Poland and South China and the fossil record of the Hurdiidae}, journal = {PeerJ}, volume = {9}, year = {2021}, pages = {e11800}, abstract = {

The Furongian period represents an important gap in the fossil record of most groups of non-biomineralizing organisms, owing to a scarcity of Konservat-Lagerst{\"a}tten of that age. The most significant of these deposits, the Jiangshanian strata of the Sandu Formation near Guole Township (Guangxi, South China), have yielded a moderately abundant, but taxonomically diverse soft-bodied fossil assemblage, which provides rare insights into the evolution of marine life at that time. In this contribution, we report the first discovery of a radiodont fossil from the Guole Konservat-Lagerst{\"a}tte. The specimen is an incomplete frontal appendage of a possibly new representative of the family Hurdiidae. It is tentatively interpreted as composed of seven podomeres, six of which bearing laminiform endites. The best preserved of these endites is especially long, and it bears short auxiliary spines that greatly vary in size. This is the second occurrence of hurdiids and more generally radiodonts in the Furongian, the first being the external mould of an oral cone from Jiangshanian strata of the Wi{\'s}ni{\'o}wka Sandstone Formation in Poland. Restudy of this Polish specimen confirms that it belongs to a hurdiid radiodont and best compares to Peytoia. The family Hurdiidae includes the oldest (basal Cambrian Epoch 2) and youngest (Early Ordovician, possibly Early Devonian) representatives of the Radiodonta and as such, has the longest stratigraphical range of the group. Yet, hurdiids only became prominent components of marine ecosystems during the middle Cambrian (Miaolingian), and their fossil record in younger strata remains limited.

}, url = {https://peerj.com/articles/11800/?utm_source=Twitter\&utm_medium=social\&utm_campaign=11800\&utm_id=PeerJ\%20Tweets}, author = {Zhu, X. and Lerosey-Aubril, R. and J. Ortega-Hern{\'a}ndez} } @article {1417763, title = {New multipodomerous appendages of stem group euarthropods from the Cambrian (Stage 4) Guanshan Konservat-Lagerst{\"a}tte}, journal = {Royal Society Open Science}, volume = {8}, year = {2021}, pages = {211134}, abstract = {

Stem-group euarthropods are important for understanding the early evolutionary and ecological history of the most species-rich animal phylum on Earth. Of particular interest are fossil taxa that occupy a phylogenetic position immediately crownwards of radiodonts, for this part of the euarthropod tree is associated with the appearance of several morphological features that characterize extant members of the group. Here, we report two new euarthropods from the Cambrian Stage 4 Guanshan Biota of South China. The fuxianhuiid Alacaris? sp. is represented by isolated appendages composed of a gnathobasic protopodite and an endite-bearing endopod of at least 20 podomeres. This material represents the youngest occurrence of the family Chengjiangocarididae, and its first record outside the Chengjiang and Xiaoshiba biotas. We also describe Lihuacaris ferox gen. et sp. nov. based on well-preserved and robust isolated appendages. Lihuacaris ferox exhibits an atypical combination of characters including an enlarged rectangular base, 11 endite-bearing podomeres and a hypertrophied distal element bearing 8{\textendash}10 curved spines. Alacaris? sp. appendages display adaptations for macrophagy. Lihuacaris ferox appendages resemble the frontal appendages of radiodonts, as well as the post-oral endopods of chengjiangocaridid fuxianhuids and other deuteropods with well-documented raptorial/predatory habits. Lihuacaris ferox contributes towards the record of endemic biodiversity in the Guanshan Biota.

}, url = {https://royalsocietypublishing.org/doi/10.1098/rsos.211134}, author = {D.G. Jiao and Pates, S. and Lerosey-Aubril, R. and J. Ortega-Hern{\'a}ndez and Yang, J. and Lan, T. and Zhang, X. G.} } @article {1383321, title = {A new somasteroid from the Fezouata Lagerst{\"a}tte in Morocco and the early Ordovician origin of Asterozoa}, journal = {Biology Letters}, volume = {20200809 }, year = {2021}, abstract = {

The somasteroids are Lower Palaeozoic star-shaped animals widely regarded as ancestors of Asterozoa, the group of echinoderms that includes brittle stars and starfish. However, the origin of asterozoans, the assembly of their distinctive body organization, and their relationships with other Cambrian and Ordovician echinoderms remain problematic owing to the difficulties of comparing the endoskeleton between disparate groups. Here, we describe the new somasteroid Cantabrigiaster fezouataensis, a primitive asterozoan from the Early Ordovician Fezouata Lagerst{\"a}tte in Morocco. Cantabrigiaster shares with other somasteroids a unique endoskeletal arm organization and the presence of rod-like virgal ossicles that articulate with the ambulacrals, but differs from all other known asterozoans in the absence of adambulacral ossicles defining the arm margins, evoking parallels with non-asterozoan echinoderms. Developmentally informed Bayesian and parsimony phylogenetic analyses, which reflect the homology of the biserial ambulacral ossicles in Palaeozoic echinoderms according to the extraxial{\textendash}axial theory, recover Cantabrigiaster as the earliest divergent stem-group asterozoan. Our results illuminate the ancestral morphology of Asterozoa, and clarify the affinities of problematic Ordovician Asterozoa. Bayesian inference and parsimony demonstrate that somasteroids represent a paraphyletic grade within stem- and crown-group Asterozoa, whereas stenuroids are paraphyletic within stem-group Ophiuroidea. Our results also offer potential insights on the evolutionary relationships between asterozoans, crinoids and potential Cambrian stem-group representatives.

}, url = {https://royalsocietypublishing.org/doi/10.1098/rsbl.2020.0809}, author = {A.W. Hunter and J. Ortega-Hern{\'a}ndez} } @article {1373835, title = {Paleoecologic and paleoenvironmental implications of a new trace fossil recording infaunal moulting in Devonian marginal-marine settings}, journal = {Palaeogeography, Palaeoclimatology, Palaeoecology}, volume = {561}, year = {2021}, pages = {110043}, abstract = {

Luancaia igen. Nov. and its two new ichnospecies, L. candasensis and L. elongata, from the Middle Devonian Naranco Formation of Asturias, northern Spain, record infaunal moulting most likely related to a defensive strategy. The new ichnogenus has an elongate to oblong outline, and displays a distinctly trilobate appearance that includes an axial longitudinal lobe characterized by a distinctive ridge flanked by lateral lobes at each side. Well-defined transverse ridges convey a metameric-like appearance consisting of up to nine distinct segments. The anterior-most part is more variable, but consistently features a pair of oval strongly convex, or a subtriangular fan-like ridge in well-preserved specimens.

Luancaia is similar to Rusophycus in its general segmented appearance, suggesting a euarthropod producer, but differs in the presence of a distinctive axial ridge and in the absence of scratch imprints. Luancaia closely resembles the dorsal side of the enigmatic Carboniferous oniscid-like euarthropod Camptophyllia. We propose that Luancaia records supine (i.e. upside-down) infaunal moulting of a euarthropod with a dorsal exoskeletal morphology similar to Camptophyllia, in which exuviation was facilitated by dorsal anchoring on a firm muddy substrate.

The Naranco Formation records sedimentation in a shallow- and marginal-marine setting that at times was affected by fluvial discharge most likely during storm floods. In particular, Luancaia is preserved in storm-flood beds that accumulated in relative proximity to a river mouth. These latter deposits consist of sparsely bioturbated sandstone and mudstone that reflect deposition under stressful conditions, such as salinity stress, high sedimentation rate, and turbidity. By burrowing into the sediment, the producer avoided the stressed physical conditions of the sediment surface. Marginal-marine settings, where competition and predation pressures were significantly lower than in adjacent fully marine environments, may have served as safe moulting sites during the mid-Paleozoic marine radiation.

}, url = {https://www.sciencedirect.com/science/article/abs/pii/S0031018220304910}, author = {M. G. M{\'a}ngano and L. Pi{\~n}uela and L. A. Buatois and J. Ortega-Hern{\'a}ndez and F. J. Rodr{\'\i}guez-Tovar and J.C. Garc{\'\i}a-Ram} } @article {1415867, title = {A tardigrade in Dominican amber}, journal = {Proceedings of the Royal Society B }, volume = {288}, year = {2021}, pages = {20211760 }, abstract = {Tardigrades are a diverse group of charismatic microscopic invertebrates that
are best known for their ability to survive extreme conditions. Despite their
long evolutionary history and global distribution in both aquatic and terrestrial
environments, the tardigrade fossil record is exceedingly sparse. Molecular
clocks estimate that tardigrades diverged from other panarthropod lineages
before the Cambrian, but only two definitive crown-group representatives
have been described to date, both from Cretaceous fossil deposits in North
America. Here, we report a third fossil tardigrade from Miocene age
Dominican amber. Paradoryphoribius chronocaribbeus gen. et sp. nov. is the
first unambiguous fossil representative of the diverse superfamily Isohypsibioidea,
as well as the first tardigrade fossil described from the Cenozoic. We
propose that the patchy tardigrade fossil record can be explained by the preferential
preservation of these microinvertebrates as amber inclusions, coupled
with the scarcity of fossiliferous amber deposits before the Cretaceous.}, url = {https://royalsocietypublishing.org/doi/10.1098/rspb.2021.1760}, author = {M. A. Mapalo and N. Robin and B. E. Boudinot and J. Ortega-Hern{\'a}ndez and P. A. Barden} } @article {1303636, title = {Computer tomography sheds new light on the affinities of the enigmatic euarthropod Jianshania furcatus from the early Cambrian Chengjiang biota}, journal = {BMC Evolutionary Biology}, volume = {20}, year = {2020}, abstract = {

Background

The Chengjiang biota is one of the most species-rich Cambrian Konservat-Lagerst{\"a}tten, and preserves a community dominated by non-biomineralized euarthropods. However, several Chengjiang euarthropods have an unfamiliar morphology, are extremely rare, or incompletely preserved.

Results

We employed micro-computed tomography to restudy the enigmatic euarthropod Jianshania furcatus. We reveal new morphological details, and demonstrate that the specimens assigned to this species represent two different taxa. The holotype of J. furcatus features a head shield with paired anterolateral notches, stalked lateral eyes, and an articulated tailspine with a bifurcate termination. The other specimen is formally redescribed as Xiaocaris luoi gen. et sp. nov., and is characterized by stalked eyes connected to an anterior sclerite, a subtrapezoidal head shield covering three small segments with reduced tergites, a trunk with 15 overlapping tergites with a well-developed dorsal keel, and paired tail flukes.

Conclusions

The presence of antennae, biramous appendages with endopods composed of 15 articles, and multiple appendage pairs associated with the trunk tergites identify X. luoi nov. as a representative of Fuxianhuiida, an early branching group of stem-group euarthropods endemic to the early Cambrian of Southwest China. X. luoi nov. represents the fifth fuxianhuiid species described from the Chengjiang biota, and its functional morphology illuminates the ecological diversity of this important clade for understanding the early evolutionary history of euarthropods.

}, url = {https://bmcevolbiol.biomedcentral.com/articles/10.1186/s12862-020-01625-4}, author = {Liu, Y. and J. Ortega-Hern{\'a}ndez and H.Chen and H. Mai and D. Zhai and X. G. Hou} } @article {1377969, title = {A new early Cambrian Konservat-Lagerst{\"a}tte expands the occurrence of Burgess Shale-type deposits on the Yangtze Platform}, journal = {Earth Science Reviews}, volume = {211}, year = {2020}, pages = {103409}, abstract = {

We report the Fandian biota, a new Konservat-Lagerst{\"a}tte from the Cambrian Stage 3 Yuxiansi and Jiulaodong Formations in Sichuan, South China, with close faunal links to the Chengjiang biota in Yunnan. The biodiversity of the Fandian biota includes total-group euarthropods (radiodonts, bivalved forms, acercostracans, trilobites, non-biomineralized trilobitomorphs), armoured lobopodians, palaeoscolecids, pedunculate brachiopods, hyoliths, chancelloriids, sponges, and filamentous algae. Benthic dwellers dominate the fossil community (e.g. trilobitomorphs, brachiopods, sponges), with rare instances of nektonic (radiodonts, bivalved euarthropods) and infaunal (palaeoscolecids) organisms. The Fandian biota contains soft-bodied taxa that were only known from Chengjiang and Xiaoshiba until now, namely Primicaris (acercostracan), Xandarella (non-trilobite trilobitomorph) and Mafangscolex (palaeoscolecid), expanding the distribution of these previously endemic taxa beyond Yunnan to the northern Yangtze Platform during the Cambrian Stage 3. Our findings provide a more comprehensive understanding of early Cambrian biodiversity that inhabited the Yangtze Platform over a substantially greater palaeobiogeographic distribution than previously considered.

}, url = {https://www.sciencedirect.com/science/article/pii/S0012825220304554}, author = {K.S. Du and J. Ortega-Hern{\'a}ndez and Yang, J. and Q.H. Guo and W. Li and J.F. He and K.R. Li and J.L. Du and Hou, J. B. and Zhang, X. G.} } @article {1230301, title = {New exceptionally preserved panarthropods from the Drumian Wheeler Konservat-Lagerst{\"a}tte of the House Range of Utah}, journal = {Papers in Palaeontology}, volume = {6}, year = {2020}, pages = {501-531}, abstract = {

The Drumian Wheeler Konservat-Lagerst{\"a}tte of the House Range of Utah (Wheeler-HR) has yielded one of the most diverse exceptionally preserved Cambrian biotas of North America. The discovery of soft-bodied fossils invariably provides precious insights into this biota, given that most of its non-biomineralizing components are known from very few specimens. This contribution describes some 30 new exceptionally preserved fossils of Wheeler panarthropods. Two new species are recognized, the radiodont Hurdia sp. nov. A and the megacheiran Kanoshoia rectifrons gen. et sp. nov. Along with a species of Leanchoilia, K.\ rectifrons represents the first confident megacheiran record in these strata. The presence of the radiodont genus Amplectobelua and the isoxyid species Isoxys longissimus is reported outside of the Burgess Shale in Laurentia. New specimens of Caryosyntrips serratus, Naraoia compacta, Messorocaris magna and Mollisonia symmetrica provide insights into the phylogenetic affinities, local spatial distribution and morphological variation of these species hitherto known by single specimens in the Wheeler-HR. The same is true of new materials of the more common Pahvantia hastata and Perspicaris? dilatus. Formal descriptions of the order Mollisoniida ord. nov. and family Mollisoniidae fam. nov. are also provided. Last, the preservation of body structures other than the dorsal exoskeletons is illustrated for the first time in two common components of the fauna: the agnostid Itagnostus interstrictus and the bivalved euarthropod Pseudoarctolepis sharpi. The new material substantially improves our understanding of the diversity of the Wheeler-HR biota, and provides new evidence of its distinctiveness relative to the Wheeler biota of the Drum Mountains.

}, url = {https://onlinelibrary.wiley.com/doi/full/10.1002/spp2.1307}, author = {Lerosey-Aubril, R. and J. Kimmig and Pates, S. and J. Skabelund and A. Weug and J. Ortega-Hern{\'a}ndez} } @article {1277239, title = {Occurrence of the eudemersal radiodont Cambroraster in the early Cambrian Chengjiang Lagerst{\"a}tte and the diversity of hurdiid ecomorphotypes}, journal = {Geological Magazine}, volume = {157}, year = {2020}, pages = {1200-1206}, abstract = {Radiodonts are a diverse clade of Lower Palaeozoic stem-group euarthropods that played a key role in the emergence of complex marine trophic webs. The latest addition to the group, Cambroraster falcatus, was recently described from the Wuliuan Burgess Shale, and is characterized by a unique horseshoe-shaped central carapace element. Here we report the discovery of Cambroraster sp. nov. A, a new species from the Cambrian Stage 3 Chengjiang Lagerst{\"a}tte of South China. The new occurrence of Cambroraster demonstrates that some of the earliest known radiodonts had already evolved a highly derived carapace morphology adapted to an essentially eudemersal life as sediment foragers.}, url = {https://www.cambridge.org/core/journals/geological-magazine/article/occurrence-of-the-eudemersal-radiodont-cambroraster-in-the-early-cambrian-chengjiang-lagerstatte-and-the-diversity-of-hurdiid-ecomorphotypes/D4AD12D56D158EC7AFD9ACBA499B6A7C}, author = {Liu, Y. and Lerosey-Aubril, R. and D. Audo and D. Zhai and M. Huijuan and J. Ortega-Hern{\'a}ndez} } @article {1303637, title = {A reduced labrum in a Cambrian great-appendage euarthropod}, journal = {Current Biology}, volume = {30}, year = {2020}, pages = {3057-3061}, abstract = {
The euarthropod head is a highly versatile and functionally specialized body region composed of multiple appendage-bearing segments and whose complex evolution has been scrutinized through anatomical, developmental, and paleontological approaches [
,
,
,
]. Exceptionally preserved Cambrian fossils have allowed for the reconstruction of critical stages of the evolutionary history of the head, such as the origin of the labrum{\textemdash}an anteromedian flap-like structure that overlies the mouth opening in almost all extant representatives{\textemdash}from an ancestral pair of pre-ocular (protocerebral) appendages [
,
,
]. The highly conserved position of the labrum makes it a valuable anatomical landmark for understanding the anterior segmental organization among extant and extinct euarthropods [
]. However, the labrum is seemingly absent in the megacheirans, a major extinct group characterized by enlarged raptorial {\textquotedblleft}great appendages{\textquotedblright} with a central role in competing hypotheses on the early evolution of the head [
,
,
,
,
,
]. Here, we used micro-computed tomography to demonstrate the presence of a three-dimensionally preserved labrum associated with the mouth opening in juvenile specimens of the megacheiran Leanchoilia illecebrosa from the early Cambrian Chengjiang biota, Southwest China. The position of the labrum relative to the pre-oral great appendages of L.\ illecebrosa indicates that these limbs correspond to the deutocerebral segment and are therefore serially homologous with the first appendage pair of extant euarthropods [
,
,
,
,
]. The reduced labrum and deutocerebral great appendages of L.\ illecebrosa also strengthen the affinities of megacheirans as stem-group chelicerates, in line with recent paleoneurological fossil data from the early to mid-Cambrian of China and North America [
,
].
}, url = {https://www.cell.com/current-biology/fulltext/S0960-9822(20)30772-7}, author = {Liu, Y. and J. Ortega-Hern{\'a}ndez and D. Zhai and X. G. Hou} } @article {1286965, title = {Revision of the mollisoniid chelicerate(?) Thelxiope, with a new species from the middle Cambrian Wheeler Formation of Utah}, journal = {PeerJ}, volume = {8}, year = {2020}, pages = {e8879}, abstract = {

The recent re-interpretation of the Lower Palaeozoic euarthropod group Mollisonia as belonging to Chelicerata has triggered a renewed interest for the poorly known family Mollisoniidae. In this contribution, we revise the anatomy, taxonomic diversity, and systematics of Thelxiope, the sister-taxon of Mollisonia. This mollisoniid genus comprises four species, and is characterized by the presence of one cephalic, seven thoracic (one per tergite), and three pygidial long sagittal spines. The type species, T.\ palaeothalassia Simonetta \& Delle Cave, is a rare taxon in the Wuliuan Burgess Shale Formation of Canada, which can be recognized by the hypertrophy of a single of its sagittal spines, the posteriomost one. T. spinosa (Conway Morris \& Robison){\textendash}a species originally assigned to a distinct genus {\textquoteleft}Ecnomocaris{\textquoteright} herein synonymised with Thelxiope{\textendash}is known from a single specimen found in the Drumian Wheeler Formation of the House Range of Utah. It differs from the type-species in the hypertrophy of both the anteriormost (cephalic) and the posteriormost (third pygidial) sagittal spines. The same Wheeler strata have also yielded a single specimen of a new taxon, T. holmani sp. nov., which lacks hypertrophied sagittal spines and features blunt thoracic tergopleural tips. A putative fourth species, referred to Thelxiope sp. nov. A, extends the stratigraphical range of Thelxiope to the Lower Ordovician (Tremadocian), and its palaeographic range to West Gondwana. Currently under study, this relatively common component of the lower Fezouata Shale fauna is only briefly discussed. Features characterizing the genus Thelxiope and its components almost exclusively pertain to the sagittal spines, for the scarcity and inconsistent preservation of the Cambrian materials as-yet available preclude a confident assessment of the variability of other morphological features. The pygidium in Thelxiope and Mollisonia is not composed of four, but three tergites essentially similar to thoracic ones, except for the lack of articulations.

}, url = {https://peerj.com/articles/8879/}, author = {Lerosey-Aubril, R. and J. Skabelund and J. Ortega-Hern{\'a}ndez} } @article {1285590, title = {Trace fossil evidence for infaunal moulting in a Middle Devonian non-trilobite euarthropod}, journal = {Scientific Reports}, volume = {10}, year = {2020}, pages = {5316}, abstract = {

Trace fossils represent the primary source of information on the evolution of animal behaviour through deep time, and provide exceptional insights into complex life strategies that would be otherwise impossible to infer from the study of body parts alone. Here, we describe unusual trace fossils found in marginal-marine, storm- and river-flood deposits from the Middle Devonian Naranco Formation of Asturias (northern Spain) that constitute the first evidence for infaunal moulting in a non-trilobite euarthropod. The trace fossils are preserved in convex hyporelief, and include two main morphological variants that reflect a behavioural continuum. Morphotype 1 consists of a structure that superficially resembles a Rusophycus with an oval outline that possesses a distinctly three lobed axis with an elevated central ridge and regularly spaced transverse furrows that convey the appearance of discrete body segments. The anterior part is the most irregular region of the structure, and it is not always recorded. Morphotype 2 displays more elongated, tubular morphology. Careful observation, however, reveals that it comprises up to three successive morphotype 1 specimens organised in a linear fashion and partially truncating each other. Trilobate morphology and effaced transverse furrows are locally evident, but the predominant morphological feature is the continuous, elevated ridge. The detailed morphology of morphotype 1 and well-preserved, discrete segments of morphotype 2 closely resemble the dorsal exoskeleton of the enigmatic late Carboniferous euarthropod Camptophyllia, suggesting the possible affinities of the producer. Comparisons with patterns of Devonian phacopid trilobite exuviation suggest that the Naranco Formation trace fossils may have been produced by the infaunal activities of an euarthropod that anchored its dorsal exoskeleton in the firm sediment during the body inversion moult procedure. Our findings expand the phylogenetic and environmental occurrence of infaunal moulting in Palaeozoic euarthropods, and suggest a defensive strategy against predation, previously only known from trilobites preserved in open-marine deposits.

}, url = {https://www.nature.com/articles/s41598-020-62019-6}, author = {M. G. M{\'a}ngano and J. Ortega-Hern{\'a}ndez and L. Pi{\~n}uela and L. A. Buatois and F. J. Rodr{\'\i}guez-Tovar and J. C. Garc{\'\i}a-Ramos} } @article {1226285, title = {Appendicular anatomy of the artiopod Emeraldella brutoni from the middle Cambrian (Drumian) of western Utah}, journal = {PeerJ}, volume = {7}, year = {2019}, pages = {e7945 }, abstract = {
The non-biomineralized artiopod Emeraldella brutoni Stein, Church \& Robinson, from the middle Cambrian (Drumian) Wheeler Formation in Utah represents the only confirmed occurrence of the genus Emeraldella, outside of the stratigraphically older (Wuliuan) Burgess Shale Konservat-Lagerst{\"a}tte in British Columbia. The hitherto known sole specimen of this species is preserved in dorsal view and lacks critical information on the ventral appendages. Here we redescribe E. brutoni based on a new completely articulated specimen that illustrates the appendage organization in exceptional detail. The main body consists of a cephalic region covered by a semicircular head shield, a trunk including 10 tergites with expanded pleurae plus a cylindrical terminal segment, and a long articulated tailspine. The head carries a pair of elongate and flexible antennae, a pair of lateral eyes, and three pairs of post-antennal appendages. We report the presence of eyes in Emeraldella for the first time. The first post-antennal limb solely consists of an endopod with well-developed paired spiniform endites. The remaining cephalic appendages and those associated with all but the last trunk segments possess exopods terminating in paddle-shaped, distal lobes fringed with robust setae. The cylindrical terminal segment bears a pair of posteriorly oriented caudal flaps reminiscent of trunk exopods, and a styliform, possibly uniarticulate tailspine longer than the main body. The new data on E. brutoni suggests an exopodal origin for the paired caudal structures in Vicissicaudata, and improve our understanding of the fundamental organization of this major clade within Artiopoda.
}, url = {https://peerj.com/articles/7945/}, author = {Lerosey-Aubril, R. and J. Ortega-Hern{\'a}ndez} } @article {1217405, title = {The appendicular morphology of Sinoburius lunaris and the evolution of the artiopodan clade Xandarellida (Euarthropoda, early Cambrian) from South China}, journal = {BMC Evolutionary Biology}, volume = {19}, year = {2019}, pages = {1-20}, abstract = {

Background

Artiopodan euarthropods represent common and abundant faunal components in sites with exceptional preservation during the Cambrian. The Chengjiang biota in South China contains numerous taxa that are exclusively known from this deposit, and thus offer a unique perspective on euarthropod diversity during the early Cambrian. One such endemic taxon is the non-trilobite artiopodan Sinoburius lunaris, which has been known for approximately three decades, but few details of its anatomy are well understood due to its rarity within the Chengjiang, as well as technical limitations for the study of these fossils. Furthermore, the available material does not provide clear information on the ventral organization of this animal, obscuring our understanding of phylogenetically significant details such as the appendages.

Results

We employed X-ray computed tomography to study the non-biomineralized morphology of Sinoburius lunaris. Due to the replacement of the delicate anatomy with pyrite typical of Chengjiang fossils, computed tomography reveals substantial details of the ventral anatomy of Sinoburius lunaris, and allow us to observe in detail the three-dimensionally preserved appendicular organization of this taxon for the first time. The dorsal exoskeleton consists of a crescent-shaped head shield with well-developed genal spines, a thorax with seven freely articulating tergites, and a fused pygidium with lateral and median spines. The head bears a pair of ventral stalked eyes that are accommodated by dorsal exoskeletal bulges, and an oval elongate ventral hypostome. The appendicular organization of the head is unique among Artiopoda. The deutocerebral antennae are reduced, consisting of only five podomeres, and bear an antennal scale on the second podomere that most likely represents an exite rather than a true ramus. The head includes four post-antennal biramous limb pairs. The first two biramous appendages are differentiated from the rest. The first appendage pair consists of a greatly reduced endopod coupled with a greatly elongated exopod with a potentially sensorial function. The second appendage pair carries a more conventionally sized endopod, but also has an enlarged exopod. The remaining biramous appendages are homonomous in their construction, but decrease in size towards the posterior end of the body. They consist of a basipodite with ridge-like crescentic endites, an endopod with seven podomeres and a terminal claw, and a lamellae-bearing exopod with a slender shaft. Contrary to previous reports, we confirm the presence of segmental mismatch in Sinoburius lunaris, expressed as diplotergites in the thorax. Maximum parsimony and Bayesian phylogenetic analyses support the monophyly of Xandarellida within Artiopoda, and illuminate the internal relationships within this enigmatic clade. Our results allow us to propose a transformation series explaining the origin of archetypical xandarellid characters, such as the evolution of eye slits in Xandarella spectaculum and Phytophilaspis pergamena as derivates from the anterolateral notches in the head shield observed in Cindarella eucalla and Luohuilinella species. In this context, Sinoburius lunaris is found to feature several derived characters within the group, such as the secondary loss of eye slits and a high degree of appendicular tagmosis. Contrary to previous findings, our analyses strongly support close affinities between Sinoburius lunaris, Xandarella spectaculum and Phytophilaspis pergamena, although the precise relationships between these taxa are sensitive to different methodologies.

Conclusions

The revised morphology of Sinoburius lunaris, made possible through the use of computed tomography to resolve details of its three-dimensionally preserved appendicular anatomy, contributes towards an improved understanding of the morphology of this taxon and the evolution of Xandarellida more broadly. Our results indicate that Sinoburius lunaris possesses an unprecedented degree of appendicular tagmosis otherwise unknown within Artiopoda, with the implication that this iconic group of Palaeozoic euarthropods likely had a more complex ecology and functional morphology than previously considered. The application of computer tomographic techniques to the study of Chengjiang euarthropods holds exceptional promise for understanding the morphological diversity of these organisms, and also better reconstructing their phylogenetic relationships and evolutionary history.

}, url = {https://bmcevolbiol.biomedcentral.com/articles/10.1186/s12862-019-1491-3}, author = {X. Chen and J. Ortega-Hern{\'a}ndez and Wolfe, J. M. and D. Zhai and M. Huijian and X. G. Hou and A. Chen and L. Yu.} } @article {1161609, title = {Ecdysis in a stem-group euarthropod from the early Cambrian of South China}, journal = {Scientific Reports}, volume = {9}, year = {2019}, pages = {5709}, abstract = {

Moulting is a fundamental component of the ecdysozoan life cycle, but the fossil record of this strategy is susceptible to preservation biases, making evidence of ecdysis in soft-bodied organisms extremely rare. Here, we report an exceptional specimen of the fuxianhuiid Alacaris mirabilis preserved in the act of moulting from the Cambrian (Stage 3) Xiaoshiba Lagerst{\"a}tte, South China. The specimen displays a flattened and wrinkled head shield, inverted overlap of the trunk tergites over the head shield, and duplication of exoskeletal elements including the posterior body margins and telson. We interpret this fossil as a discarded exoskeleton overlying the carcass of an emerging individual. The moulting behaviour of A. mirabilis evokes that of decapods, in which the carapace is separated posteriorly and rotated forward from the body, forming a wide gape for the emerging individual. A. mirabilis illuminates the moult strategy of stem-group Euarthropoda, offers the stratigraphically and phylogenetically earliest direct evidence of ecdysis within total-group Euarthropoda, and represents one of the oldest examples of this growth strategy in the evolution of Ecdysozoa.

}, url = {https://www.nature.com/articles/s41598-019-41911-w}, author = {Yang, J. and J. Ortega-Hern{\'a}ndez and H. B. Drage and K.S. Du and Z. G. Zhang} } @inbook {1161610, title = {Exceptionally preserved Cambrian fossils in the genomic era}, booktitle = {Old Questions and Young Approaches to Animal Evolution}, year = {2019}, pages = {39-54}, publisher = {Springer Nature}, organization = {Springer Nature}, edition = {1st}, abstract = {

Palaeontological data plays a key role in reconstructing the biology, ecology, and evolution of the biosphere throughout the history of Life on Earth. Whereas modern molecular-based technologies have led to significant progress in understanding the developmental biology and phylogenetic relationships of extant animal phyla, Cambrian soft-bodied fossils represent the only way of studying the morphology of their extinct ancestors. This chapter provides an overview of the significance of exceptionally preserved Cambrian fossils and their contribution towards illuminating the origin of animal body plans. Over the last few decades, conceptual and technical advances have distanced Cambrian fossils away from their previous misconception as failed evolutionary experiments. Current efforts focus instead on clarifying the evolutionary links between these fascinating organisms and their extant descendants, made possible in part by the discovery of new exceptional deposits, and the improved knowledge of their unusual geological history capable of preserving delicate but informative tissues such as guts and brains.

}, url = {https://rd.springer.com/chapter/10.1007/978-3-030-18202-1_3}, author = {J. Ortega-Hern{\'a}ndez} } @article {1145303, title = {The last common ancestor of Ecdysozoa had an adult terminal mouth}, journal = {Arthropod Structure and Development}, volume = {49}, year = {2019}, pages = {155-158}, abstract = {

The Ecdysozoa is a major animal clade whose main uniting feature is a distinctive growth strategy that requires the periodical moulting of the external cuticle. The staggering diversity within Ecdysozoa has prompted substantial efforts to reconstruct their origin and early evolution. Based on palaentological and developmental data, we proposed a scenario for the early evolution of the ecdysozoan clade Panarthropoda (Onychophora, Tardigrada, Euarthropoda), and postulated that a terminal mouth is ancestral for this lineage. In light of the accompanying comment by Claus Nielsen, we take this opportunity to clarify the significance of our argumentation for Panarthropoda in the phylogenetic context of Ecdysozoa, and Bilateria more broadly. We conclude that the ancestral ecdysozoan most likely had an adult terminal mouth, and that the last common ancestors of all the phyla that constitute Ecdysozoa almost certainly also had an adult terminal mouth. The occurrence of a ventral-facing mouth in various adult ecdysozoans {\textendash} particularly panarthropods {\textendash} is the result of convergence. Despite the paucity of embryological data on fossil taxa, we contemplate the likelihood that a developmentally early ventral mouth opening could be ancestral for Ecdysozoa, and if so, then this would represent a symplesiomorphy of Bilateria as a whole.

}, url = {https://www.sciencedirect.com/science/article/pii/S1467803918301440?via\%3Dihub}, author = {J. Ortega-Hern{\'a}ndez and Janssen, R. and Budd, G. E.} } @article {1167824, title = {New insights into the evolution of lateral compound eyes in Palaeozoic horseshoe crabs}, journal = {Zoological Journal of the Linnean Society }, volume = {187}, year = {2019}, pages = {1061-1077}, abstract = {

Vision allows animals to interact with their environment. Aquatic chelicerates dominate the early record of lateral compound eyes among non-biomineralizing crown-group euarthropods. Although the conservative morphology of lateral eyes in Xiphosura is potentially plesiomorphic for Euarthropoda, synziphosurine eye organization has received little attention despite their early diverging phylogenetic position. Here, we re-evaluate the fossil evidence for lateral compound eyes in the synziphosurines Bunodes sp., Cyamocephalus loganensis, Legrandella lombardii, Limuloides limuloides, Pseudoniscus clarkei, Pseudoniscus falcatus and Pseudoniscus roosevelti. We compare these data with lateral eyes in the euchelicerates Houia yueya, Kasibelinurus amicorum and Lunataspis aurora. We find no convincing evidence for lateral eyes in most studied taxa, and Pseudoniscus roosevelti and Legrandella lombardii are the only synziphosurines with this feature. Our findings support two scenarios for euchelicerate lateral eye evolution. The elongate-crescentic lateral eyes of Legrandella lombardii might represent the ancestral organization, as suggested by the phylogenetic position of this taxon in stem-group Euchelicerata. Alternatively, the widespread occurrence of kidney-shaped lateral eyes in stem-group Xiphosura and stem-group Arachnida could represent the plesiomorphic condition; Legrandella lombardii eyes would therefore be derived. Both evolutionary scenarios support the interpretation that kidney-shaped lateral eyes are ancestral for crown-group Euchelicerata and morphologically conserved in extant Limulus polyphemus.

}, url = {https://academic.oup.com/zoolinnean/advance-article-abstract/doi/10.1093/zoolinnean/zlz065/5543300}, author = {R.D.C. Bicknell and L. Amati and J. Ortega-Hern{\'a}ndez} } @article {1123541, title = {Occurrence of the aglaspidid arthropod Beckwithia in the Furongian Guole Konservat-Lagerst{\"a}tte of South China}, journal = {Palaeoworld}, volume = {28}, year = {2019}, pages = {73-79}, abstract = {

The Aglaspidida is a major group of Palaeozoic arthropods traditionally regarded as problematic, but whose evolutionary history has attracted renewed attention over the last decade. These efforts have resulted in an improved understanding of various aspects of aglaspidid palaeobiology, including their environmental, geographical and stratigraphical distribution, and phylogenetic relationships. Here, we describe a new weakly biomineralized non-trilobite arthropod from the Furongian Guole Konservat{\textendash}Lagerst{\"a}tte (Sandu Formation) in South China that contributes towards a more complete reconstruction of aglaspidid evolution and diversity during the late Cambrian. Beckwithia? gracilis n. sp. resembles the type species B. typa in the possession of a reentrant posterior cephalic margin, general trunk appearance and coarse tuberculation, but differs in having a more slender construction and a homogeneous exoskeletal sculpture. A revision of putative Beckwithia from Australia and Russia argues against their inclusion in this taxon, making the new species the only representative of the genus outside Laurentia. After Aglaspella and Glypharthrus, also from the Guole biota, this is the third aglaspidid genus shared between Laurentia and South China, which supports the hypothesis that some aglaspidids had great dispersal capabilities.

}, url = {https://www.sciencedirect.com/science/article/pii/S1871174X18300143}, author = {X.-J. Zhu and Lerosey-Aubril, R. and J. Ortega-Hern{\'a}ndez} } @article {1232034, title = {Proclivity of nervous system preservation in Cambrian Burgess Shale-type deposits}, journal = {Proceedings of the Royal Society of London B}, volume = { 286}, year = {2019}, pages = {20192370}, url = {https://royalsocietypublishing.org/doi/10.1098/rspb.2019.2370$\#$d1218252e1}, author = {J. Ortega-Hern{\'a}ndez and Lerosey-Aubril, R. and Pates, S.} } @article {1126680, title = {A soft-bodied euarthropod from the early Cambrian Xiaoshiba Lagerst{\"a}tte of China supports a new clade of basal artiopodans with dorsal ecdysial sutures}, journal = {Cladistics}, volume = {35}, year = {2019}, pages = {269-281}, abstract = {

We describe the exceptionally well-preserved non-trilobite artiopodan Zhiwenia coronata gen. et sp. nov. from the Cambrian Stage 3 Xiaoshiba Lagerst{\"a}tte in Yunnan, China. The exoskeleton consists of a cephalic shield with dorsal sutures expressed as\ lateral notches that accommodate stalked lateral eyes, an elongate trunk composed of 20 tergites{\textemdash}the first of which is reduced{\textemdash}and a short tailspine with marginal spines. Appendicular data include a pair of multi-segmented antennae, and homonomous biramous trunk limbs consisting of an endopod with at least seven podomeres and a flattened exopod with lamellae. Although the presence of cephalic notches and a reduced first trunk tergite invites comparisons with the petalopleurans Xandarella, Luohiniella and Cindarella, the proportions and exoskeletal tagmosis of Zhiwenia do not closely resemble those of any major group within Trilobitomorpha. Parsimony and Bayesian phylogenetic analyses consistently support Zhiwenia as sister-taxon to the Emu Bay Shale artiopodan Australimicola spriggi, and both of them as closely related to Acanthomeridion from the Chengjiang. This new monophyletic clade, Protosutura nov., occupies a basal phylogenetic position within Artiopoda as sister-group to Trilobitomorpha and Vicissicaudata, illuminates the ancestral organization of these successful euarthropods, and leads to a re-evaluation of the evolution of ecdysial dorsal sutures within the group.

}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/cla.12344}, author = {K.S. Du and J. Ortega-Hern{\'a}ndez and Yang, J. and Zhang, X. G.} } @article {1145102, title = {Three-dimensionally preserved appendages in an early Cambrian stem-group pancrustacean}, journal = {Current Biology}, volume = {29}, year = {2019}, pages = {171-177}, abstract = {
{\textbullet} The Chengjiang euarthropod Ercaicunia multinodosa preserves appendages in 3D
}, url = {https://www.cell.com/current-biology/fulltext/S0960-9822(18)31590-2}, author = {D. Zhai and J. Ortega-Hern{\'a}ndez and Wolfe, J. M. and X. G. Hou and C. J. Cao and Liu, Y.} } @article {1116018, title = {Gut glands illuminate trunk segmentation in Cambrian fuxianhuiids}, journal = {Current Biology}, volume = {28}, year = {2018}, pages = {R135-R147}, abstract = {

The euarthropod body consists of serially repeated segments with various degrees of functional specialization and regionalization [1] . Some representatives exhibit deviant metameric patterns expressed as an indirect correspondence between components of the exoskeleton, usually the number or position of dorsoventral sclerotized plates and walking legs ( Supplemental Information ) [1{\textendash}3] . Segmental mismatch in the form of supernumerary walking legs per tergite (i.e. dorsal exoskeletal plate) is characteristic of fuxianhuiids, Cambrian euarthropods widely regarded as critical for understanding the origin of this phylum [4,5] . The broader significance of this organization remains obscure, however, due to the difficulty of distinguishing which components of the fuxianhuiid trunk reflect ancestral or derived traits. Here, we describe for the first time the presence of metameric midgut diverticulae in Fuxianhuia protensa from the Chengjiang Konservat-Lagerst{\"a}tte and demonstrate that these digestive structures follow the segmentation pattern of the dorsal exoskeleton. Midgut diverticulae signal a predatory or scavenging ecology [6,7] , falsifying the view of fuxianhuiids as simple mud-feeders [4] . Comparison with other euarthropods [1{\textendash}3,5] indicates that fuxianhuiids possessed a unique mode of exoskeletal and visceral segmental mismatch, in which the tergites and midgut were segmentally patterned independently from the walking legs and ventral nerve cord. Our findings provide direct evidence of substantial developmental flexibility among stem-group euarthropods during the Cambrian.

}, url = {http://www.cell.com/current-biology/fulltext/S0960-9822(18)30073-3}, author = {J. Ortega-Hern{\'a}ndez and D.J. Fu and X. L. Zhang and D. Shu} } @newspaperarticle {1132663, title = {La Explosi{\'o}n del C{\'a}mbrico y el origen de la biosfera moderna}, volume = {77}, year = {2018}, pages = {8}, abstract = {La Tierra ha sido habitada por organismos vivientes por al menos 3 mil 500 millones de a{\~n}os (Ma)1. La vida ha evolucionado de forma dram{\'a}tica durante este tiempo, diversific{\'a}ndose y adapt{\'a}ndose a ambientes altamente din{\'a}micos, y simult{\'a}neamente transformando la estructura f{\'\i}sica y qu{\'\i}mica de dichos h{\'a}bitats. En este contexto, el registro f{\'o}sil adquiere una importancia incomparable, dado que captura evidencia directa sobre la evoluci{\'o}n y diversificaci{\'o}n de la vida en la Tierra en una escala de tiempo profundo. El origen de los animales representa una de las mayores contribuciones del registro f{\'o}sil, no solamente porque este grupo biol{\'o}gico incluye a los seres humanos como especie, sino por el tremendo efecto que estos complejos organismos han tenido en modelar las interacciones que definen el funcionamiento global de la biosfera durante los {\'u}ltimos 500 Ma y que se mantienen hoy en d{\'\i}a.}, url = {http://saberesyciencias.com.mx/2018/07/09/la-explosion-del-cambrico-origen-la-biosfera-moderna/}, author = {J. Ortega-Hern{\'a}ndez} } @article {1115975, title = {Anamorphic development and extended parental care in a 520 million-year-old stem-group euarthropod from China}, journal = {BMC Evolutionary Biology}, volume = {18}, year = {2018}, month = {16 Feb 2018}, pages = {147}, abstract = {

Extended parental care (XPC) is a complex reproductive strategy in which progenitors actively look after their offspring up to - or beyond - the first juvenile stage in order to maximize their fitness. Although the euarthropod fossil record has produced several examples of brood-care, the appearance of XPC within this phylum remains poorly constrained given the scarcity of developmental data for Palaeozoic stem-group representatives that would link juvenile and adult forms in an ontogenetic sequence. Here, we describe the post-embryonic growth of Fuxianhuia protensa from the early Cambrian Chengjiang Lagerst{\"a}tte, and show parental care in this stem-group euarthropod. We recognize fifteen distinct ontogenetic stages based on the number and shape of the trunk tergites, and their allocation between the morphologically distinct thorax and abdomen. Our data demonstrate anamorphic post-embryonic development in F. protensa, in which tergites were sequentially added from a posterior growth zone. A life assemblage consisting of a sexually mature F. protensa adult alongside four ontogenetically coeval juveniles, constitutes the oldest occurrence of XPC in the panarthropod fossil record. These findings provide the most phylogenetically basal evidence of anamorphosis in the evolutionary history of total-group Euarthropoda, and reveal a complex post-embryonic reproductive ecology for its early representatives.

}, url = {https://bmcevolbiol.biomedcentral.com/articles/10.1186/s12862-018-1262-6}, author = {D.J. Fu and J. Ortega-Hern{\'a}ndez and Daley, A.C. and Z. L. Zhang and D. Shu} } @article {1114530, title = {Early Cambrian fuxianhuiids from China reveal origin of the gnathobasic protopodite in euarthropods}, journal = {Nature Communications}, volume = {9}, year = {2018}, pages = {470}, abstract = {Euarthropods owe their evolutionary and ecological success to the morphological plasticity of
their appendages. Although this variability is partly expressed in the specialization of the
protopodite for a feeding function in the post-deutocerebral limbs, the origin of the former
structure among Cambrian representatives remains uncertain. Here, we describe Alacaris
mirabilis gen. et sp. nov. from the early Cambrian Xiaoshiba Lagerst{\"a}tte in China, which
reveals the proximal organization of fuxianhuiid appendages in exceptional detail. Proximally,
the post-deutocerebral limbs possess an antero-posteriorly compressed protopodite with
robust spines. The protopodite is attached to an endopod with more than a dozen podomeres,
and an oval flap-shaped exopod. The gnathal edges of the protopodites form an axial
food groove along the ventral side of the body, indicating a predatory/scavenging autecology.
A cladistic analysis indicates that the fuxianhuiid protopodite represents the phylogenetically
earliest occurrence of substantial proximal differentiation within stem-group Euarthropoda
illuminating the origin of gnathobasic feeding.}, url = {https://www.nature.com/articles/s41467-017-02754-z}, author = {Yang, J. and J. Ortega-Hern{\'a}ndez and Legg, D. A. and Lan, T. and J.-b. Hou and X.-g.Zhang} } @article {1126681, title = {Fuxianhuiids}, journal = {Current Biology}, volume = {28}, year = {2018}, pages = {R724-R725}, abstract = {The fuxianhuiids {\textemdash} of which there are eight species described so far {\textemdash}are a clade of extinct soft-bodied euarthropods (colloquially: arthropods) that are known
from early Cambrian marine deposits in South China (Figure 1). They are widely
regarded as distant relatives of extant euarthropod groups {\textemdash} namely arachnids,
myriapods, crustaceans and insects. The exceptional preservation of their fossils
has provided unique information on their morphology (Figure 2). Fuxianhuiids
have contributed towards a better understanding of the early evolutionary
radiation of euarthropods {\textemdash}the most successful animal phylum in the history
of life on Earth {\textemdash} and led to a detailed reconstruction of the origin of the
euarthropod body plan.}, url = {https://www.cell.com/current-biology/fulltext/S0960-9822(18)30514-1}, author = {J. Ortega-Hern{\'a}ndez and Yang, J. and Zhang, X. G.} } @article {1114655, title = {Reply to Comment on {\textquotedblleft}Aysheaia prolata from the Utah Wheeler Formation (Drumian, Cambrian) is a frontal appendage of the radiodontan Stanleycaris{\textquotedblright} with the formal description of Stanleycaris}, journal = {Acta Palaeontologica Polonica}, volume = {63}, year = {2018}, abstract = {As part of a comprehensive examination of all radiodontans
from Cambrian localities in the USA, Pates et al. (2017a, b)
and Pates and Daley (2017) revised the taxonomic affinities
of several described specimens. This included the reinterpretation
of two putative lobopodians, one from the Wheeler
Formation (Utah, USA) and one from the Valdemiedes Formation
(Spain), as frontal appendages of the radiodontan
genera Stanleycaris and Caryosyntrips respectively. In their
comment, G{\'a}mez Vintaned and Zhuravlev (2018) disagree
with these conclusions and raise three topics for discussion:
(i) anatomical features they suggest support a lobopodian
affinity for {\textquotedblleft}Mureropodia{\textquotedblright}; (ii) the identity of Caryosyntrips
as a radiodontan, and the assignment of certain specimens to
this genus; and (iii) the nomenclatural status of Stanleycaris
hirpex as an invalid taxon. For (i), we dispute that the anatomical
features put forward by G{\'a}mez Vintaned and Zhuravlev
(2018) are biological and conclude that a lobopodian
affinity for Mureropodia is untenable. In response to (ii), we
provide further evidence supporting a radiodontan affinity
for Caryosyntrips, and those specimens ascribed to this genus.
Finally, we concur with (iii) Stanleycaris as an invalid
taxon according to the International Code on Zoological
Nomenclature (ICZN), and have rectified the situation by
providing a valid systematic description.}, url = {https://www.app.pan.pl/article/item/app004432017.html}, author = {Pates, S. and Daley, A.C. and J. Ortega-Hern{\'a}ndez} } @article {1127142, title = {The Weeks Formation Konservat-Lagerst{\"a}tte and the evolutionary transition of Cambrian marine life}, journal = {Journal of the Geological Society }, volume = {175}, year = {2018}, pages = {705-715}, abstract = {
The Weeks Formation in Utah is the youngest (c. 499 Ma) and least studied Cambrian Lagerst{\"a}tte of the western United States. It preserves a diverse exceptionally-preserved fauna that inhabited a relatively deep-water environment at the offshore margin of a carbonate platform, resembling the setting of the underlying Wheeler and Marjum formations. Yet, the Weeks fauna differs significantly in composition from the other remarkable biotas of Cambrian Series 3 of Utah, suggesting a significant Guzhangian faunal restructuring. This bioevent is regarded as the onset of a transitional episode in the history of life, separating the two primary diversifications of the Early Palaeozoic. The Weeks fossils have been strongly affected by late diagenetic processes, but some specimens still preserve exquisite anatomical details.
}, url = {http://jgs.lyellcollection.org/content/early/2018/05/18/jgs2018-042}, author = {Lerosey-Aubril, R. and R. Gaines and T. A. Hegna and J. Ortega-Hern{\'a}ndez and Van Roy, P. and Kier, C. and Bonino, E.} } @article {1086246, title = {Corrigendum: A xandarellid artiopodan from Morocco - a middle Cambrian link between soft-bodied euarthropod communities in North Africa and South China}, journal = {Scientific Reports}, volume = {7}, year = {2017}, note = {Ortega-Hernandez, JavierAzizi, AbdelfattahHearing, Thomas WHarvey, Thomas H PEdgecombe, Gregory DHafid, AhmidEl Hariri, KhadijaengPublished ErratumEngland2017/05/10 06:00Sci Rep. 2017 May 9;7:46797. doi: 10.1038/srep46797.}, month = {May 09}, pages = {46797}, isbn = {2045-2322 (Electronic)2045-2322 (Linking)}, author = {J. Ortega-Hern{\'a}ndez and Azizi, A. and Hearing, T. W. and Harvey, T. H. P. and G.D. Edgecombe and Hafid, A. and El Hariri, K.} } @article {1086351, title = {Aysheaia prolata from the Wheeler Formation (Cambrian, Drumian) is a frontal appendage of the radiodontan Stanleycaris}, journal = {Acta Palaeontologica Polonica}, volume = {62}, year = {2017}, pages = {619-625}, abstract = {Aysheaia prolata, was described as the only lobopodian from the Drumian (Cambrian) Wheeler Formation in Utah, USA, and the sole representative of this genus besides the type species\ Aysheaia pedunculata, from the Cambrian (Stage 5) Stephen Formation, British Columbia. A redescription of\ Aysheaia prolata\ reveals previously overlooked morphological features, including segmental boundaries between putative lobopods, and curved terminal spines on the putative anterior end. These observations undermine lobopodian affinities of\ Aysheaia prolata, and instead we interpret this specimen as an isolated radiodontan frontal appendage. The presence of 11 podomeres, five of which possess elongate and anteriorly recurved ventral blades with auxiliary spines, together with shorter robust dorsal spines, identify the specimen as\ Stanleycaris. This represents the first report of\ Stanelycaris\ outside of the Cambrian Stage 5 thin Stephen Formation in British Columbia, expanding its palaeobiogeographic and stratigraphic range.\ Aysheaia\ is left as a monotypic genus endemic to the Burgess Shale. The Spence Shale luolishaniid\ Acinocrinus stichus\ is currently the only lobopodian known from the Cambrian of Utah.}, author = {Pates, S. and Daley, A.C. and J. Ortega-Hern{\'a}ndez} } @article {1086256, title = {Origin and evolution of the panarthropod head - A palaeobiological and developmental perspective}, journal = {Arthropod Structure and Development}, volume = {46}, number = {3}, year = {2017}, note = {Ortega-Hernandez, JavierJanssen, RalfBudd, Graham EengReviewEngland2016/12/19 06:00Arthropod Struct Dev. 2017 May;46(3):354-379. doi: 10.1016/j.asd.2016.10.011. Epub 2016 Dec 18.}, month = {May}, pages = {354-379}, abstract = {The panarthropod head represents a complex body region that has evolved through the integration and functional specialization of the anterior appendage-bearing segments. Advances in the developmental biology of diverse extant organisms have led to a substantial clarity regarding the relationships of segmental homology between Onychophora (velvet worms), Tardigrada (water bears), and Euarthropoda (e.g. arachnids, myriapods, crustaceans, hexapods). The improved understanding of the segmental organization in panarthropods offers a novel perspective for interpreting the ubiquitous Cambrian fossil record of these successful animals. A combined palaeobiological and developmental approach to the study of the panarthropod head through deep time leads us to propose a consensus hypothesis for the intricate evolutionary history of this important tagma. The contribution of exceptionally preserved brains in Cambrian fossils - together with the recognition of segmentally informative morphological characters - illuminate the polarity for major anatomical features. The euarthropod stem-lineage provides a detailed view of the step-wise acquisition of critical characters, including the origin of a multiappendicular head formed by the fusion of several segments, and the transformation of the ancestral protocerebral limb pair into the labrum, following the postero-ventral migration of the mouth opening. Stem-group onychophorans demonstrate an independent ventral migration of the mouth and development of a multisegmented head, as well as the differentiation of the deutocerebral limbs as expressed in extant representatives. The anterior organization of crown-group Tardigrada retains several ancestral features, such as an anterior-facing mouth and one-segmented head. The proposed model aims to clarify contentious issues on the evolution of the panarthropod head, and lays the foundation from which to further address this complex subject in the future.}, keywords = {(Eu)arthropod head problem, *Biological Evolution, Animals, Arthropods/*anatomy \& histology/classification/embryology, Cambrian, Fossils, Head/*anatomy \& histology, Lobopodians, Mouth/anatomy \& histology, Onychophora, Phylogeny, Stem-group Euarthropoda, Tardigrada}, isbn = {1873-5495 (Electronic)1467-8039 (Linking)}, author = {J. Ortega-Hern{\'a}ndez and Janssen, R. and Budd, G. E.} } @article {1086231, title = {The Vicissicaudata revisited - insights from a new aglaspidid arthropod with caudal appendages from the Furongian of China}, journal = {Scientific Reports}, volume = {7}, number = {1}, year = {2017}, note = {Lerosey-Aubril, RudyZhu, XuejianOrtega-Hernandez, JavierengEngland2017/09/13 06:00Sci Rep. 2017 Sep 11;7(1):11117. doi: 10.1038/s41598-017-11610-5.}, month = {Sep 11}, pages = {11117}, abstract = {Cambrian marine ecosystems were dominated by arthropods, and more specifically artiopods. Aglaspidids represent an atypical group amongst them, not the least because they evolved and rapidly diversified during the late Cambrian, a time interval between the two diversification events of the Early Palaeozoic. Recent phylogenetic analyses have retrieved aglaspidids within the Vicissicaudata, a potentially important, but difficult to define clade of artiopods. Here we describe a new aglaspidid from the Furongian Guole Konservat-Lagerstatte of South China. This taxon displays a pretelsonic segment bearing non-walking appendages, features as-yet known in all vicissicaudatans, but aglaspidids. A new comprehensive phylogenetic analysis provides strong support for the legitimacy of a monophyletic clade Vicissicaudata, and demonstrates the pertinence of new characters to define Aglaspidida. It also motivates important changes to the systematics of the phylum, including the elevation of Artiopoda to the rank of subphylum, and the establishment of a new superclass Vicissicaudata and a new aglaspidid family Tremaglaspididae. Two diversification pulses can be recognized in the early history of artiopods - one in the early Cambrian (trilobitomorphs) and the other in the late Cambrian (vicissicaudatans). The discrepancy between this pattern and that traditionally depicted for marine invertebrates in the Early Palaeozoic is discussed.}, isbn = {2045-2322 (Electronic)2045-2322 (Linking)}, author = {Lerosey-Aubril, R. and Zhu, X. and J. Ortega-Hern{\'a}ndez} } @inbook {1090956, title = {What is the point of phylogenies?}, booktitle = {52 More Things You Should Know About Palaeontology}, year = {2017}, pages = {110-111}, publisher = {Agile Libre}, organization = {Agile Libre}, address = {Nova Scotia, Canada}, author = {J. Ortega-Hern{\'a}ndez} } @article {1086241, title = {A xandarellid artiopodan from Morocco - a middle Cambrian link between soft-bodied euarthropod communities in North Africa and South China}, journal = {Scientific Reports}, volume = {7}, year = {2017}, note = {Ortega-Hernandez, JavierAzizi, AbdelfattahHearing, Thomas WHarvey, Thomas H PEdgecombe, Gregory DHafid, AhmidEl Hariri, KhadijaengEngland2017/02/18 06:00Sci Rep. 2017 Feb 17;7:42616. doi: 10.1038/srep42616.}, month = {Feb 17}, pages = {42616}, abstract = {Xandarellida is a well-defined clade of Lower Palaeozoic non-biomineralized artiopodans that is exclusively known from the early Cambrian (Stage 3) Chengjiang biota of South China. Here we describe a new member of this group, Xandarella mauretanica sp. nov., from the middle Cambrian (Stage 5) Tatelt Formation of Morocco, making this the first non-trilobite Cambrian euarthropod known from North Africa. X. mauretanica sp. nov. represents the youngest occurrence of Xandarellida - extending its stratigraphic range by approximately 10 million years - and expands the palaeobiogeographic distribution of the group to the high southern palaeolatitudes of West Gondwana. The new species provides insights into the lightly sclerotized ventral anatomy of Xandarellida, and offers stratigraphically older evidence for a palaeobiogeographic connection between Burgess Shale-type euarthropod communities in North Africa and South China, relative to the (Tremadocian) Fezouata biota.}, isbn = {2045-2322 (Electronic)2045-2322 (Linking)}, author = {J. Ortega-Hern{\'a}ndez and Azizi, A. and Hearing, T. W. and Harvey, T. H. and G.D. Edgecombe and Hafid, A. and El Hariri, K.} } @article {1087331, title = {The enigmatic lobopodian Hallucigenia and the origin of velvet worms}, journal = {Fundamental}, volume = {29}, year = {2016}, pages = {1-46}, author = {J. Ortega-Hern{\'a}ndez and Smith, M. R.} } @article {1086266, title = {Fuxianhuiid ventral nerve cord and early nervous system evolution in Panarthropoda}, journal = {Proceedings of the National Academy of Sciences U S A}, volume = {113}, number = {11}, year = {2016}, note = {Yang, JieOrtega-Hernandez, JavierButterfield, Nicholas JLiu, YuBoyan, George SHou, Jin-BoLan, TianZhang, Xi-GuangengResearch Support, Non-U.S. Gov{\textquoteright}t2016/03/05 06:00Proc Natl Acad Sci U S A. 2016 Mar 15;113(11):2988-93. doi: 10.1073/pnas.1522434113. Epub 2016 Mar 1.}, month = {Mar 15}, pages = {2988-93}, abstract = {Panarthropods are typified by disparate grades of neurological organization reflecting a complex evolutionary history. The fossil record offers a unique opportunity to reconstruct early character evolution of the nervous system via exceptional preservation in extinct representatives. Here we describe the neurological architecture of the ventral nerve cord (VNC) in the upper-stem group euarthropod Chengjiangocaris kunmingensis from the early Cambrian Xiaoshiba Lagerstatte (South China). The VNC of C. kunmingensis comprises a homonymous series of condensed ganglia that extend throughout the body, each associated with a pair of biramous limbs. Submillimetric preservation reveals numerous segmental and intersegmental nerve roots emerging from both sides of the VNC, which correspond topologically to the peripheral nerves of extant Priapulida and Onychophora. The fuxianhuiid VNC indicates that ancestral neurological features of Ecdysozoa persisted into derived members of stem-group Euarthropoda but were later lost in crown-group representatives. These findings illuminate the VNC ground pattern in Panarthropoda and suggest the independent secondary loss of cycloneuralian-like neurological characters in Tardigrada and Euarthropoda.}, keywords = {*Fossils, Animals, Biological Evolution, Cambrian Explosion, China, Ganglia, Invertebrate/anatomy \& histology, Nervous System/*anatomy \& histology, Onychophora, Phylogeny, Species Specificity, Stem-group Euarthropoda, Tardigrada/*anatomy \& histology, Xiaoshiba Lagerstatte}, isbn = {1091-6490 (Electronic)0027-8424 (Linking)}, author = {Yang, J. and J. Ortega-Hern{\'a}ndez and Butterfield, N. J. and Liu, Y. and Boyan, G. S. and Hou, J. B. and Lan, T. and Zhang, X. G.} } @article {1086291, title = {Making sense of {\textquoteright}lower{\textquoteright} and {\textquoteright}upper{\textquoteright} stem-group Euarthropoda, with comments on the strict use of the name Arthropoda von Siebold, 1848}, journal = {Biological Reviews}, volume = {91}, number = {1}, year = {2016}, note = {Ortega-Hernandez, JavierengResearch Support, Non-U.S. Gov{\textquoteright}tEngland2014/12/23 06:00Biol Rev Camb Philos Soc. 2016 Feb;91(1):255-73. doi: 10.1111/brv.12168. Epub 2014 Dec 21.}, month = {Feb}, pages = {255-73}, abstract = {The ever-increasing number of studies that address the origin and evolution of Euarthropoda - whose extant representatives include chelicerates, myriapods, crustaceans and hexapods - are gradually reaching a consensus with regard to the overall phylogenetic relationships of some of the earliest representatives of this phylum. The stem-lineage of Euarthropoda includes numerous forms that reflect the major morphological transition from a lobopodian-type to a completely arthrodized body organization. Several methods of classification that aim to reflect such a complex evolutionary history have been proposed as a consequence of this taxonomic diversity. Unfortunately, this has also led to a saturation of nomenclatural schemes, often in conflict with each other, some of which are incompatible with cladistic-based methodologies. Here, I review the convoluted terminology associated with the classification of stem-group Euarthropoda, and propose a synapomorphy-based distinction that allows {\textquoteright}lower stem-Euarthropoda{\textquoteright} (e.g. lobopodians, radiodontans) to be separated from {\textquoteright}upper stem-Euarthropoda{\textquoteright} (e.g. fuxianhuiids, Cambrian bivalved forms) in terms of the structural organization of the head region and other aspects of overall body architecture. The step-wise acquisition of morphological features associated with the origins of the crown-group indicate that the node defining upper stem-Euarthropoda is phylogenetically stable, and supported by numerous synapomorphic characters; these include the presence of a deutocerebral first appendage pair, multisegmented head region with one or more pairs of post-ocular differentiated limbs, complete body arthrodization, posterior-facing mouth associated with the hypostome/labrum complex, and post-oral biramous arthropodized appendages. The name {\textquoteright}Deuteropoda{\textquoteright} nov. is proposed for the scion (monophyletic group including the crown-group and an extension of the stem-group) that comprises upper stem-Euarthropoda and Euarthropoda. A brief account of common terminological inaccuracies in recent palaeontological studies evinces the utility of Deuteropoda nov. as a reference point for discussing aspects of early euarthropod phylogeny.}, keywords = {*Biological Evolution, *Terminology as Topic, Aiolopoda, Animal Structures, Animals, arthrodization, Arthropods/*classification/genetics, crown-group, Deuteropoda nov, Euarthropoda, Fossils, lobopodian, Onychophora, Panarthropoda, Phylogeny, Tardigrada}, isbn = {1469-185X (Electronic)0006-3231 (Linking)}, author = {J. Ortega-Hern{\'a}ndez} } @article {1086251, title = {The nature of non-appendicular anterior paired projections in Palaeozoic total-group Euarthropoda}, journal = {Arthropod Structure and Development}, volume = {45}, number = {2}, year = {2016}, note = {Ortega-Hernandez, JavierBudd, Graham EengResearch Support, Non-U.S. Gov{\textquoteright}tEngland2016/01/24 06:00Arthropod Struct Dev. 2016 Mar;45(2):185-199. doi: 10.1016/j.asd.2016.01.006. Epub 2016 Jan 21.}, month = {Mar}, pages = {185-199}, abstract = {Recent studies have clarified the segmental organization of appendicular and exoskeletal structures in the anterior region of Cambrian stem-group Euarthropoda, and thus led to better understanding of the deep evolutionary origins of the head region in this successful animal group. However, there are aspects of the anterior organization of Palaeozoic euarthropods that remain problematic, such as the morphological identity and significance of minute limb-like projections on the anterior region in stem and crown-group representatives. Here, we draw attention to topological and morphological similarities between the frontal filaments of extant Crustacea and the embryonic frontal processes of Onychophora, and distinctive anterior paired projections observed in several extinct total-group Euarthropoda. Anterior paired projections are redescribed in temporally and phylogenetically distant fossil taxa, including the gilled lobopodians Kerygmachela kierkegaardi and Pambdelurion whittingtoni, the bivalved stem-euarthropod Canadaspis perfecta, the larval pycnogonid Cambropycnogon klausmuelleri, and the mandibulate Tanazios dokeron. Developmental data supporting the homology of the {\textquoteright}primary antennae{\textquoteright} of Onychophora, the {\textquoteright}frontal appendages{\textquoteright} of lower-stem Euarthropoda, and the hypostome/labrum complex of Deuteropoda, argue against the morphological identity of the anterior paired projections of extant and extinct panarthropods as a pair of pre-ocular appendages. Instead, we regard the paired projections of fossil total-group euarthropods as non-appendicular evaginations with a likely protocerebral segmental association, and a possible sensorial function. The widespread occurrence of pre-ocular paired projections among extant and extinct taxa suggests their potential homology as fundamentally ancestral features of the anterior body organization in Panarthropoda. Non-appendicular paired projections with a sensorial function may reflect a critical--yet previously overlooked--component of the panarthropod ground pattern.}, keywords = {(Eu)arthropod head problem, Animals, Arthropods/*anatomy \& histology/growth \& development/ultrastructure, Branchiopoda, Cirripedia, Extremities/anatomy \& histology/growth \& development, Fossils/*anatomy \& histology/ultrastructure, Frontal filaments, Frontal processes, Gilled lobopodian, Head/anatomy \& histology/growth \& development, Microscopy, Electron, Scanning, Onychophora, Primary antennae, Protocerebrum, Remipedia}, isbn = {1873-5495 (Electronic)1467-8039 (Linking)}, author = {Ortega-Hernandez, J. and Budd, G. E.} } @article {1086366, title = {A new aglaspidid euarthropod with a six-segmented trunk from the Lower Ordovician Fezouata Konservat-Lagerst{\"a}tte, Morocco}, journal = {Geological Magazine}, volume = {153}, year = {2016}, pages = {524-536}, abstract = {A new euarthropod with an uncommon morphology,\ Brachyaglaspis singularis\ gen. et sp. nov., is described from the Early Ordovician (middle Floian) Fezouata biota of Morocco. The presence of a pair of postventral plates, widely attached to each other and located under the posterior-most trunk tergite and the base of the tailspine, indicates a phylogenetic relationship with the enigmatic group Aglaspidida. The overall morphology of\ Brachyaglaspis\ most closely resembles that of the {\textquoteleft}Ordovician-type{\textquoteright} aglaspidids, more specifically the late Cambrian {\textendash} Early Ordovician genus\ Tremaglaspis. However, the presence of a prominent cephalon and only six trunk tergites in the new genus deviates from the organization of all other known aglaspidid species, notably extending the known range of morphological disparity of the group. A taxonomic revision of this euarthropod group indicates that the most accurate name and authorship combination correspond to Aglaspidida Walcott, 1912.}, author = {Ortega-Hernandez, J. and Van Roy, P. and Lerosey-Aubril, R.} } @article {1086271, title = {A predatory bivalved euarthropod from the Cambrian (Stage 3) Xiaoshiba Lagerstatte, South China}, journal = {Scientific Reports}, volume = {6}, year = {2016}, note = {Yang, Jie, Ortega-Hernandez, Javier, Lan, Tian, Hou, Jin-Bo, Zhang, Xi-Guang eng England2016/06/11 06:00Sci Rep. 2016 Jun 10;6:27709. doi: 10.1038/srep27709.}, month = {Jun 10}, pages = {27709}, abstract = {Bivalved euarthropods represent a conspicuous component of exceptionally-preserved fossil biotas throughout the Lower Palaeozoic. However, most of these taxa are known from isolated valves, and thus there is a limited understanding of their morphological organization and palaeoecology in the context of early animal-dominated communities. The bivalved euarthropod Clypecaris serrata sp. nov., recovered from the Cambrian (Stage 3) Hongjingshao Formation in Kunming, southern China, is characterized by having a robust first pair of raptorial appendages that bear well-developed ventral-facing spines, paired dorsal spines on the trunk, and posteriorly oriented serrations on the anteroventral margins of both valves. The raptorial limbs of C. serrata were adapted for grasping prey employing a descending stroke for transporting it close the mouth, whereas the backwards-facing marginal serrations of the bivalved carapace may have helped to secure the food items during feeding. The new taxon offers novel insights on the morphology of the enigmatic genus Clypecaris, and indicates that the possession of paired dorsal spines is a diagnostic trait of the Family Clypecarididae within upper stem-group Euarthropoda. C. serrata evinces functional adaptations for an active predatory lifestyle within the context of Cambrian bivalved euarthropods, and contributes towards the better understanding of feeding diversity in early ecosystems.}, isbn = {2045-2322 (Electronic)2045-2322 (Linking)}, author = {Yang, J. and Ortega-Hernandez, J. and Lan, T. and Hou, J. B. and Zhang, X. G.} } @article {1086286, title = {Homology of head sclerites in Burgess Shale euarthropods}, journal = {Current Biology}, volume = {25}, number = {12}, year = {2015}, note = {Ortega-Hernandez, Javier eng Research Support, Non-U.S. Gov{\textquoteright}t England 2015/05/12 06:00Curr Biol. 2015 Jun 15;25(12):1625-31. doi: 10.1016/j.cub.2015.04.034. Epub 2015 May 7.}, month = {Jun 15}, pages = {1625-31}, abstract = {The Cambrian fossil record of euarthropods (extant arachnids, myriapods, crustaceans, hexapods) has played a major role in understanding the origins of these successful animals and indicates that early ancestors underwent an evolutionary transition from soft-bodied taxa (lobopodians) to more familiar sclerotized forms with jointed appendages [1-3]. Recent advances in paleoneurology and developmental biology show that this major transformation is reflected by substantial changes in the head region of early euarthropods, as informed by the segmental affinity of the cephalic appendages [1, 4-6]. However, data on the implications of this reorganization for non-appendicular exoskeletal structures are lacking, given the difficulty of inferring the precise segmental affinities of these features. Here, I report neurological remains associated with the stalked eyes and "anterior sclerite" in the (middle Cambrian) Burgess Shale euarthropods Helmetia expansa and Odaraia alata and provide evidence that these features are associated with nerve traces originating from the anterior brain region, the protocerebrum. The position of the protocerebral ganglia in exceptionally preserved Cambrian euarthropods indicates the homology of the anterior sclerite in extinct groups (e.g., fuxianhuiids, bivalved forms, artiopodans [7, 8]) and allows new comparisons with the dorsal cephalic plate of radiodontans, large nektonic predators whose anterior segmental organization bears fundamental similarities to that of Paleozoic lobopodians [1, 6, 9, 10]. These observations allow reconstruction of the segmental architecture of the head region in the earliest sclerotized euarthropods and demonstrate the deep homology between exoskeletal features in an evolutionary continuum of taxa with distinct types of body organization.}, keywords = {Animals, anterior sclerite, Arthropods/*anatomy \& histology, Artiopoda, Biological Evolution, Brain/anatomy \& histology, Burgess Shale, frontal organ, Fuxianhuiida, Head/*anatomy \& histology, hypostome/labrum complex, median eye, paleoneurology, Protocerebrum, Radiodonta, Stem-group Euarthropoda}, isbn = {1879-0445 (Electronic)0960-9822 (Linking)}, author = {Ortega-Hernandez, J.} } @article {1086281, title = {Lobopodians}, journal = {Current Biology}, volume = {25}, number = {19}, year = {2015}, note = {Ortega-Hernandez, JavierengEngland2015/10/07 06:00Curr Biol. 2015 Oct 5;25(19):R873-5. doi: 10.1016/j.cub.2015.07.028.}, month = {Oct 05}, pages = {R873-5}, keywords = {*Biological Evolution, Animals, Arthropods/anatomy \& histology/classification, Fossils/*anatomy \& histology, Invertebrates/*anatomy \& histology/*classification, Phylogeny}, isbn = {1879-0445 (Electronic)0960-9822 (Linking)}, author = {Ortega-Hernandez, J.} } @article {1086376, title = {A rare non-trilobite artiopodan from the Guzhangian (Cambrian Series 3) Weeks Formation Konservat-Lagerst{\"a}tte in Utah, USA}, journal = {Palaeontology}, volume = {58}, year = {2015}, pages = {265-276}, abstract = {We describe a weakly biomineralized non-trilobite artiopodan arthropod from the Guzhangian Weeks Formation of Utah.\ Falcatamacaris bellua\ gen. et sp. nov. is typified by a thin calcitic cuticle, broad cephalon without eyes or dorsal ecdysial sutures, an elongate trunk with distinctively sickle-shaped pleural spines and a long tailspine with a bifurcate termination. The precise affinities of\ Falcatamacaris\ gen. nov. are problematic due to the presence of unique features within Artiopoda, such as the peculiar morphology of the pleural and posterior regions of the trunk. Possible affinities with aglaspidid-like arthropods and concilitergans are discussed based on the possession of 11 trunk tergites, edge-to-edge articulations and overall body spinosity. The new taxon highlights the importance of the Weeks Formation Konservat-Lagerst{\"a}tte for further understanding the diversity of extinct arthropod groups in the upper Cambrian.}, author = {Ortega-Hernandez, J. and Lerosey-Aubril, R. and Kier, C. and Bonino, E.} } @article {1086316, title = {A superarmored lobopodian from the Cambrian of China and early disparity in the evolution of Onychophora}, journal = {Proceedings of the National Academy of Sciences U S A}, volume = {112}, number = {28}, year = {2015}, note = {Yang, JieOrtega-Hernandez, JavierGerber, SylvainButterfield, Nicholas JHou, Jin-BoLan, TianZhang, Xi-guangengResearch Support, Non-U.S. Gov{\textquoteright}t2015/07/01 06:00Proc Natl Acad Sci U S A. 2015 Jul 14;112(28):8678-83. doi: 10.1073/pnas.1505596112. Epub 2015 Jun 29.}, month = {Jul 14}, pages = {8678-83}, abstract = {We describe Collinsium ciliosum from the early Cambrian Xiaoshiba Lagerstatte in South China, an armored lobopodian with a remarkable degree of limb differentiation including a pair of antenna-like appendages, six pairs of elongate setiferous limbs for suspension feeding, and nine pairs of clawed annulated legs with an anchoring function. Collinsium belongs to a highly derived clade of lobopodians within stem group Onychophora, distinguished by a substantial dorsal armature of supernumerary and biomineralized spines (Family Luolishaniidae). As demonstrated here, luolishaniids display the highest degree of limb specialization among Paleozoic lobopodians, constitute more than one-third of the overall morphological disparity of stem group Onychophora, and are substantially more disparate than crown group representatives. Despite having higher disparity and appendage complexity than other lobopodians and extant velvet worms, the specialized mode of life embodied by luolishaniids became extinct during the Early Paleozoic. Collinsium and other superarmored lobopodians exploited a unique paleoecological niche during the Cambrian explosion.}, keywords = {*Arthropods/classification, *Biological Evolution, *Fossils, Animals, Cambrian Explosion, China, Collins{\textquoteright} monster, Evolution, Phylogeny, Xiaoshiba Lagerstatte}, isbn = {1091-6490 (Electronic)0027-8424 (Linking)}, author = {Yang, J. and Ortega-Hernandez, J. and Gerber, S. and Butterfield, N. J. and Hou, J. B. and Lan, T. and Zhang, X. G.} } @article {1086306, title = {Hallucigenia{\textquoteright}s onychophoran-like claws and the case for Tactopoda}, journal = {Nature}, volume = {514}, number = {7522}, year = {2014}, note = {Smith, Martin ROrtega-Hernandez, JavierengResearch Support, Non-U.S. Gov{\textquoteright}tEngland2014/08/19 06:00Nature. 2014 Oct 16;514(7522):363-6. doi: 10.1038/nature13576. Epub 2014 Aug 17.}, month = {Oct 16}, pages = {363-6}, abstract = {The Palaeozoic form-taxon Lobopodia encompasses a diverse range of soft-bodied {\textquoteright}legged worms{\textquoteright} known from exceptional fossil deposits. Although lobopodians occupy a deep phylogenetic position within Panarthropoda, a shortage of derived characters obscures their evolutionary relationships with extant phyla (Onychophora, Tardigrada and Euarthropoda). Here we describe a complex feature in the terminal claws of the mid-Cambrian lobopodian Hallucigenia sparsa--their construction from a stack of constituent elements--and demonstrate that equivalent elements make up the jaws and claws of extant Onychophora. A cladistic analysis, informed by developmental data on panarthropod head segmentation, indicates that the stacked sclerite components in these two taxa are homologous-resolving hallucigeniid lobopodians as stem-group onychophorans. The results indicate a sister-group relationship between Tardigrada and Euarthropoda, adding palaeontological support to the neurological and musculoskeletal evidence uniting these disparate clades. These findings elucidate the evolutionary transformations that gave rise to the panarthropod phyla, and expound the lobopodian-like morphology of the ancestral panarthropod.}, keywords = {*Fossils, *Phylogeny, Animals, Arthropods/*anatomy \& histology/*classification, Hoof and Claw/*anatomy \& histology}, isbn = {1476-4687 (Electronic)0028-0836 (Linking)}, author = {Smith, M. R. and Ortega-Hernandez, J.} } @article {1086401, title = {Corals from the early Cretaceous (Barremian {\textendash} early Albian) of Puebla, Mexico: Introduction and Family Stylinidae.}, journal = {Revista Mexicana de Ciencias Geol{\'o}gicas }, volume = {30}, year = {2013}, pages = {385-403}, abstract = {The present contribution is the first instalment of a systematic revision of the Early Cretaceous (Barremian to Early Albian) corals of Puebla, Mexico. The coral fauna preserved in the Tehuac{\'a}n region represents one of the most species rich associations of its kind from the Early Cretaceous of the New World. This article provides a brief overview of the research history, geology, lithostratigraphy and biostratigraphy, and reports the presence of corals of the family Stylinidae (suborder Stylinina). The family is represented by the genera Acanthocoenia (one species), Enallhelia (two species), Stylangia (one species) and Stylina (six species).}, author = {L{\"o}ser, H. and Garc{\'\i}a-Barrera, P. and Mendoza-Rosales, C.C. and Ortega-Hernandez, J.} } @article {1086386, title = {Occurrence of the Ordovician-type aglaspidid Tremaglaspis in the Cambrian Weeks Formation (Utah, USA).}, journal = {Geological Magazine}, volume = {150}, year = {2013}, pages = {945-951}, abstract = {

The Guzhangian Weeks Formation preserves a diverse, yet virtually unstudied, non-trilobite arthropod fauna. Here we describe\ Tremaglaspis vanroyi\ sp. nov., the oldest representative of an enigmatic group of extinct arthropods, the Aglaspidida.\ Tremaglaspis\ was previously known from the Lower Ordovician and its morphology was regarded as particularly derived within the clade. Its occurrence in the Cambrian of Utah suggests that much of the early evolutionary history of the Aglaspidida remains unknown. A review of the environmental settings of previous aglaspidid findings suggests that these arthropods preferentially inhabited shallow-water environments, which may partially explain their limited fossil record.

}, author = {Lerosey-Aubril, R. and Ortega-Hernandez, J. and Kier, C. and Bonino, E.} } @article {1086381, title = {The phylogeny of aglaspidid arthropods and the internal relationships within Artiopoda}, journal = {Cladistics}, volume = {29}, year = {2013}, pages = {15-45}, abstract = {The phylogenetic position of aglaspidids, a problematic group of Lower Palaeozoic arthropods of undetermined affinities, is re-examined in the context of the major Cambrian and Ordovician lamellipedian arthropod groups. A cladistic analysis of ten genera of aglaspidids\ sensu stricto, six aglaspidid-like arthropods and 42 Palaeozoic arthropod taxa indicates that Xenopoda, Cheloniellida, Aglaspidida\ sensu lato\ and Trilobitomorpha form a clade (Artiopoda\ Hou and Bergstr{\"o}m, 1997) nested within the mandibulate stem-lineage, thus discarding previous interpretations of these taxa as part {\textquoteright}of the chelicerate stem-group (Arachnomorpha\ Heider, 1913). The results confirm an aglaspidid identity for several recently described arthropods, including\ Quasimodaspis brentsae,\ Tremaglaspis unite,\ Chlupacaris dubia,\ Australaglaspis stonyensis\ and an unnamed Ordovician Chinese arthropod. The problematic Bohemian arthropod\ Kodymirus vagans\ was recovered as sister taxon to\ Beckwithia typa, and both form a small clade that falls outside Aglaspidida\ sensu stricto, thus discarding eurypterid affinities for the former. The analysis does not support the phylogenetic position of\ Kwanyinaspis maotianshanensis\ at the base of Conciliterga as proposed in recent studies, but rather occupies a basal position within Aglaspidida\ sensu lato.\ The results indicate a close association of aglaspidid arthropods with xenopods (i.e.\ Emeraldella\ and\ Sidneyia) and cheloniellids (e.g.\ Cheloniellon,\ Duslia); the new clade {\textquotedblleft}Vicissicaudata{\textquotedblright} is proposed to encompass these arthropods, which are characterized by a differentiated posterior region. The phylogenetic position of aglaspidid arthropods makes them good outgroup candidates for analysing the internal relationships within the groups that form Trilobitomorpha. This work provides a much clearer picture of the phylogenetic relationships among Lower Palaeozoic lamellipedians.}, author = {Ortega-Hernandez, J. and Legg, D. A. and Braddy, S.J.} } @article {1086391, title = {The first aglaspidid sensu stricto from the Cambrian of China (Sandu Shale, Guangxi).}, journal = {Geological Magazine}, volume = {150}, year = {2013}, pages = {565-571}, abstract = {

Aglaspidids represent an obscure group of lower Palaeozoic arthropods with a patchy biogeographic distribution. Before the recent description of a representative from Tasmania, these arthropods were exclusively known from Laurentia during the late Cambrian. Here we describe a new species,\ Aglaspella sanduensis\ sp. nov., from the Furongian of China, confirming that aglaspidids\ sensu stricto\ were already widely distributed worldwide by the late Cambrian; this demonstrates that some aglaspidids had great dispersal capabilities. A new diagnosis of the genus\ Aglaspella\ is proposed and the species formerly known as\ Aglaspella eatoni\ is assigned to a new taxon,\ Hesselboniagen. nov.

}, author = {Lerosey-Aubril, R. and Ortega-Hernandez, J. and Zhu, X-J} } @article {1086301, title = {Humble origins for a successful strategy: complete enrolment in early Cambrian olenellid trilobites}, journal = {Biology Letters}, volume = {9}, number = {5}, year = {2013}, note = {Ortega-Hernandez, JavierEsteve, JorgeButterfield, Nicholas JengResearch Support, Non-U.S. Gov{\textquoteright}tEngland2013/09/27 06:00Biol Lett. 2013 Sep 25;9(5):20130679. doi: 10.1098/rsbl.2013.0679. Print 2013 Oct 23.}, month = {Oct 23}, pages = {20130679}, abstract = {Trilobites are typified by the behavioural and morphological ability to enrol their bodies, most probably as a defence mechanism against adverse environmental conditions or predators. Although most trilobites could enrol at least partially, there is uncertainty about whether olenellids-among the most phylogenetically and stratigraphically basal representatives-could perform this behaviour because of their poorly caudalized trunk and scarcity of coaptative devices. Here, we report complete-but not encapsulating-enrolment for the olenellid genus Mummaspis from the early Cambrian Mural Formation in Alberta, the earliest direct evidence of this strategy in the fossil record of polymerid trilobites. Complete enrolment in olenellids was achieved through a combination of ancestral morphological features, and thus provides new information on the character polarity associated with this key trilobite adaptation.}, keywords = {*Biological Evolution, *Fossils, Alberta, Animals, Arthropods/*anatomy \& histology/physiology, Behavior, Animal/*physiology, functional morphology, Lower Dyeran, Motor Activity/*physiology, Mummaspis, Mural formation, Species Specificity}, isbn = {1744-957X (Electronic)1744-9561 (Linking)}, author = {Ortega-Hernandez, J. and Esteve, J. and Butterfield, N. J.} } @article {1086411, title = {A revision of the late Ordovician marrellomorph arthropod Furca bohemica from Czech Republic}, journal = {Acta palaeontologica Polonica}, volume = {58}, year = {2013}, pages = {615-628}, abstract = {The enigmatic marrellomorph arthropod\ Furca bohemica\ from the Upper Ordovician Letn{\'a} Formation, is redescribed. Based on existing museum specimens and new material collected from the southern slope of Ostr{\'y} Hill (Beroun, Czech Republic), the morphology and taphonomy of\ F. bohemica\ is reappraised and expanded to produce a new anatomical interpretation. The previously distinct taxa\ F. pilosa\ and\ Furca\ sp., are synonymised with\ F. bohemica,\ the latter being represented by a tapho-series in which decay has obscured some of the diagnostic features. A cladistic analysis indicates close affinities between\ F. bohemica\ and the Hunsr{\"u}ck Slate marrellomorph\ Mimetaster hexagonalis,\ together forming the Family Mimetasteridae, contrary to previous models for marrellomorph internal relationships. As with other representatives of the group, the overall anatomy of\ F. bohemica\ is consistent with a benthic, or possibly nektobenthic, mode of life. The depositional setting of the Letn{\'a} Formation indicates that\ F. bohemica\ inhabited a shallow marine environment, distinguishing it palaeoecologically from all other known marrellomorphs, which have been reported from the continental shelf.}, author = {Rak, {\v S}. and Ortega-Hernandez, J. and Legg, D. A.} } @article {1086311, title = {Specialized appendages in fuxianhuiids and the head organization of early euarthropods}, journal = {Nature}, volume = {494}, number = {7438}, year = {2013}, note = {Yang, JieOrtega-Hernandez, JavierButterfield, Nicholas JZhang, Xi-guangengHistorical ArticleResearch Support, Non-U.S. Gov{\textquoteright}tEngland2013/03/01 06:00Nature. 2013 Feb 28;494(7438):468-71. doi: 10.1038/nature11874.}, month = {Feb 28}, pages = {468-71}, abstract = {The organization of the head provides critical data for resolving the phylogenetic relationships and evolutionary history of extinct and extant euarthropods. The early Cambrian-period fuxianhuiids are regarded as basal representatives of stem-group Euarthropoda, and their anterior morphology therefore offers key insights for reconstructing the ancestral condition of the euarthropod head. However, the paired post-antennal structures in Fuxianhuia protensa remain controversial; they have been interpreted as both {\textquoteright}great appendages{\textquoteright} and as gut diverticulae. Here we describe Chengjiangocaris kunmingensis sp. nov. and Fuxianhuia xiaoshibaensis sp. nov. from a new early Cambrian (Stage 3) fossil Lagerstatte in Yunnan, China. Numerous specimens of both species show a unique {\textquoteright}taphonomic dissection{\textquoteright} of the anterodorsal head shield, revealing the cephalic organization in detail. We demonstrate the presence of a pair of specialized post-antennal appendages (SPAs) in the fuxianhuiid head, which attach at either side of the posteriorly directed mouth, behind the hypostome. Preserved functional articulations indicate a well-defined but restricted range of limb movement, suggestive of a simple type of sweep feeding. The organization of the SPAs in fuxianhuiids is incompatible with the (deutocerebral) anterior raptorial appendages of megacheirans, and argue against the presence of protocerebral limbs in the fuxianhuiids. The positions of the fuxianhuiid antennae and SPAs indicate that they are segmentally homologous to the deutocerebral and tritocerebral appendages of crown-group Euarthropoda respectively. These findings indicate that antenniform deutocerebral appendages with many podomeres are a plesiomorphic feature of the ancestral euarthropod head.}, keywords = {*Fossils, Animal Structures/*anatomy \& histology/physiology, Animals, Arthropods/*anatomy \& histology/classification/physiology, China, Digestive System/anatomy \& histology, Extremities/*anatomy \& histology/physiology, Feeding Behavior/physiology, Head/*anatomy \& histology/physiology, History, Ancient, Mouth/anatomy \& histology/physiology, Movement, Phylogeny}, isbn = {1476-4687 (Electronic)0028-0836 (Linking)}, author = {Yang, J. and Ortega-Hernandez, J. and Butterfield, N. J. and Zhang, X. G.} } @article {1092271, title = {Burgess Shale-type microfossils from the middle Cambrian Kaili Formation, Guizhou Province, China}, journal = {Acta Palaeontologica Polonica }, volume = {57 }, year = {2012}, pages = {423-436}, abstract = {

Diverse carbonaceous microfossils, including exceptionally preserved remains of non-biomineralizing metazoans, are reported from a basal middle Cambrian interval of the Kaili Formation (Guizhou Province, China). The application of a gentle acid maceration technique complements previous palynological studies by revealing a larger size-class of acritarchs, a richer assemblage of filamentous microfossils, and a variety of previously unrecovered forms. Metazoan fossils include Wiwaxia sclerites and elements derived from biomineralizing taxa, including chancelloriids, brachiopods and hyolithids, in common with previously studied assemblages from the early and middle Cambrian of Canada. In addition, the Kaili Formation has yielded pterobranch remains and an assemblage of cuticle fragments representing {\textquotedblleft}soft-bodied{\textquotedblright} worms, including a priapulid-like scalidophoran. Our results demonstrate the wide distribution and palaeobiological importance of microscopic {\textquotedblleft}Burgess Shale-type{\textquotedblright} fossils, and provide insights into the limitations and potential of this largely untapped preservational mode.

}, url = {http://www.bioone.org/doi/abs/10.4202/app.2011.0028}, author = {Harvey, T. H. P. and J. Ortega-Hern{\'a}ndez and J.-P. Lin and Y.-L. Zhao and Butterfield, N. J.} } @article {1086296, title = {Ancestral patterning of tergite formation in a centipede suggests derived mode of trunk segmentation in trilobites}, journal = {PLoS One}, volume = {7}, number = {12}, year = {2012}, note = {Ortega-Hernandez, JavierBrena, CarloengResearch Support, Non-U.S. Gov{\textquoteright}t2013/01/04 06:00PLoS One. 2012;7(12):e52623. doi: 10.1371/journal.pone.0052623. Epub 2012 Dec 28.}, pages = {e52623}, abstract = {Trilobites have a rich and abundant fossil record, but little is known about the intrinsic mechanisms that orchestrate their body organization. To date, there is disagreement regarding the correspondence, or lack thereof, of the segmental units that constitute the trilobite trunk and their associated exoskeletal elements. The phylogenetic position of trilobites within total-group Euarthropoda, however, allows inferences about the underlying organization in these extinct taxa to be made, as some of the fundamental genetic processes for constructing the trunk segments are remarkably conserved among living arthropods. One example is the expression of the segment polarity gene engrailed, which at embryonic and early postembryonic stages is expressed in extant panarthropods (i.e. tardigrades, onychophorans, euarthropods) as transverse stripes that define the posteriormost region of each trunk segment. Due to its conservative morphology and allegedly primitive trunk tagmosis, we have utilized the centipede Strigamia maritima to study the correspondence between the expression of engrailed during late embryonic to postembryonic stages, and the development of the dorsal exoskeletal plates (i.e. tergites). The results corroborate the close correlation between the formation of the tergite borders and the dorsal expression of engrailed, and suggest that this association represents a symplesiomorphy within Euarthropoda. This correspondence between the genetic and phenetic levels enables making accurate inferences about the dorsoventral expression domains of engrailed in the trunk of exceptionally preserved trilobites and their close relatives, and is suggestive of the widespread occurrence of a distinct type of genetic segmental mismatch in these extinct arthropods. The metameric organization of the digestive tract in trilobites provides further support to this new interpretation. The wider evolutionary implications of these findings suggest the presence of a derived morphogenetic patterning mechanism responsible for the reiterated occurrence of different types of trunk dorsoventral segmental mismatch in several phylogenetically distant, extinct and extant, arthropod groups.}, keywords = {Animals, Arthropods/*embryology/*genetics, Biological Evolution, Body Patterning/*genetics, Gene Expression Regulation, Developmental}, isbn = {1932-6203 (Electronic)1932-6203 (Linking)}, author = {Ortega-Hernandez, J. and Brena, C.} } @article {1087336, title = {Patterns in Palaeontology: Parsimony and palaeobiology}, journal = {Palaeontology [online]}, volume = {2}, year = {2012}, pages = {1-10}, url = {https://www.palaeontologyonline.com/articles/2012/patterns-in-palaeontology-parsimony-and-palaeobiology/}, author = {Ortega-Hernandez, J.} } @article {1087341, title = {Fossils Explained: Rudists}, journal = {Geology Today}, volume = {27}, year = {2011}, note = {doi: 10.1111/j.1365-2451.2011.00790.x}, pages = {74-77}, author = {Ortega-Hernandez, J.} } @article {1086276, title = {Lobopodian phylogeny reanalysed}, journal = {Nature}, volume = {476}, number = {7359}, year = {2011}, note = {Legg, David AMa, XiaoyaWolfe, Joanna MOrtega-Hernandez, JavierEdgecombe, Gregory DSutton, Mark DengCommentEngland2011/08/13 06:00Nature. 2011 Aug 10;476(7359):E2-3; discussion E3-4. doi: 10.1038/nature10267.}, month = {Aug 10}, pages = {E1}, keywords = {*Phylogeny, Animals, Arthropods/anatomy \& histology/*classification, Fossils, Pseudopodia/*classification, Reproducibility of Results}, isbn = {1476-4687 (Electronic)0028-0836 (Linking)}, author = {Legg, D. A. and Ma, X. and Wolfe, J. M. and Ortega-Hernandez, J. and G.D. Edgecombe and Sutton, M. D.} } @article {1087346, title = {Fossils Explained: Euthycarcinoids}, journal = {Geology Today}, volume = {26}, year = {2010}, pages = {195-198}, author = {Ortega-Hernandez, J. and Legg, D. A. and Tremewan, J.S. and Braddy, S.J.} } @article {1086431, title = {A new aglaspidid arthropod from the upper Cambrian of Tasmania}, journal = {Palaeontology}, volume = {53}, year = {2010}, pages = {1065-1076}, abstract = {The aglaspidid arthropod,\ Australaglaspis stonyensis\ gen. et sp. nov., is described from the Idamean (Upper Cambrian) of Stony Point, Montagu, north-western Tasmania. The dorsal exoskeleton comprises a semicircular cephalon with a well-defined marginal rim, acute genal angles, oval eyes, subtriangular glabella area and a subtrapezoidal hypostome. The trunk bears eleven somites with well-developed pleural spines that progressively curve backwards. Paired postventral plates cover the last trunk tergites and the base of the tailspine, which is long and characterized by a medial cleft. Bilobed ventral impressions indicate the presence of homopodous appendages, forming a food groove along the trunk. The fossil assemblage and its mode of preservation suggest that\ Australaglaspis\ originally possessed a phosphatic cuticle, but chemical traces of it have been lost because of regional metamorphism and weathering.\ Australaglaspis\ appears to be closely related to the North American aglaspidid\ Chraspedops modesta\ Raasch, 1939, based on its medially cleft tailspine.}, author = {Ortega-Hernandez, J. and Braddy, S.J. and Jago, J.B. and Baillie, P.W.} } @article {1086426, title = {Trilobite and xiphosuran affinities for the putative aglaspidid arthropods Caryon and Drabovaspis from the upper Ordovician of the Czech Republic}, journal = {Lethaia}, volume = {43}, year = {2010}, pages = {427-431}, author = {Ortega-Hernandez, J. and Braddy, S.J. and Rak, {\v S}.} } @article {1087356, title = {Misplaced trace fossils in unlikely environments}, journal = {Geology Today}, volume = {25}, year = {2009}, pages = {71-74}, author = {Ortega-Hernandez, J.} } @article {1087351, title = {Urban fossil hunting}, journal = {Rockwatch Magazine }, volume = {52}, year = {2009}, pages = {8-9}, author = {Ortega-Hernandez, J.} }