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Bicknell RD, Gaines RR, Hopkins MJ. Late Ordovician eurypterid preserves oldest euchelicerate musculature in pyrite. Biol Lett 2024; 20:20240211. [PMID: 38982848 PMCID: PMC11252848 DOI: 10.1098/rsbl.2024.0211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2024] [Accepted: 05/20/2024] [Indexed: 07/11/2024] Open
Abstract
Pyritization of soft tissues of invertebrates is rare in the fossil record. In New York State, it occurs in black shales of the Lorraine Group (Late Ordovician), the best-known example of which is Beecher's Trilobite Bed. Exceptional preservation at the quarry where this bed is exposed allowed detailed examination of trilobite and ostracod soft-tissue anatomy. Here, we present the first example of a eurypterid (sea scorpion) currently ascribed to Carcinosomatidae from this deposit that also preserves the first evidence for mesosomal musculature in eurypterids. This specimen demonstrates that eurypterid musculature can be preserved in pyrite and evidences the oldest example of euchelicerate muscles within the fossil record. Sulfur isotope data illustrate that pyrite rapidly replicated muscle tissue in the early burial environment, prior to the pyritization of biomineralized exoskeleton and cuticular trilobite limbs. This discovery therefore expands the limited fossil record of euchelicerate musculature, while extending the taphonomic scope for preservation of detailed internal structures, more broadly, within arthropods.
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Affiliation(s)
- Russell D. C. Bicknell
- Division of Paleontology (Invertebrates), American Museum of Natural History, New York, NY 10024, USA
- Palaeoscience Research Centre, School of Environmental and Rural Science, University of New England, Armidale, New South Wales 2351, Australia
| | - Robert R. Gaines
- Geology Department, Pomona College, 185 E. Sixth Street, Claremont, CA 91711, USA
| | - Melanie J. Hopkins
- Division of Paleontology (Invertebrates), American Museum of Natural History, New York, NY 10024, USA
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2
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Losso SR, Ortega-Hernández J. Conserved exopodite morphology in three-dimensionally preserved trilobites from the Walcott-Rust Quarry (Mohawkian, Ordovician) of New York, USA. ARTHROPOD STRUCTURE & DEVELOPMENT 2024; 81:101371. [PMID: 39033632 DOI: 10.1016/j.asd.2024.101371] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2024] [Revised: 06/07/2024] [Accepted: 06/17/2024] [Indexed: 07/23/2024]
Abstract
Trilobites were extremely abundant and diverse euarthropods from the Paleozoic Era, but our understanding of their non-biomineralized ventral morphology is restricted to localities with exceptional fossil preservation. The Ordovician-aged Walcott-Rust Quarry in New York State preserves exceptional trilobite fossils as calcite casts in three-dimensions with little to no deformation, providing a valuable view of their ventral morphology. Appendages of the two most abundant trilobites, Ceraurus pleurexanthemus and Flexicalymene senaria, have been known for over 150 years but the original preparation of the specimens as thin sections has led to significant disagreement about their anatomy. Ceraruus pleurexanthemus is more abundant in the thin section collections (157 specimens) and features nearly complete appendages including a subtriangular protopodite with stud-like gnathobases along the medial edge and long endites ventrally. The exopodite consists of a long proximal article bearing dumbbell-shaped lamellae (in cross section) and a shorter distal article, closely resembling that of the cheirurid Anacheirurus adserai from the Lower Ordovician Fezouata Shale biota of Morocco. The appendages of F. senaria (37 specimens) are less well preserved. The exopodite bears up to 40 dumbbell shaped lamellae (in cross section) and is proportionally longer relative to the endopodite of C. pleurexanthemus. The close morphological similarity observed between the exopodites of C. pleurexanthemus and A. adersai, despite originating from paleogeographically distant latitudes and temporally separated by over ca. 20 million years, shows that the proposed "Cambrian type" exopodite persisted through the majority of the Ordovician. The morphology of the endopodites between C. pleurexanthemus and A. adersai is more variable when compared to the organization of the exopodites, may reflect selective pressures from locomotion and feeding between these species.
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Affiliation(s)
- Sarah R Losso
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA.
| | - Javier Ortega-Hernández
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA.
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3
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Losso SR, Affatato P, Nanglu K, Ortega-Hernández J. Convergent evolution of ventral adaptations for enrolment in trilobites and extant euarthropods. Proc Biol Sci 2023; 290:20232212. [PMID: 38113938 PMCID: PMC10730288 DOI: 10.1098/rspb.2023.2212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Accepted: 11/24/2023] [Indexed: 12/21/2023] Open
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-Rust Quarry in New York State, USA. Walcott-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' wedge-shaped protopodite simultaneously facilitated tight enrolment and gnathobasic feeding with the trunk appendages.
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Affiliation(s)
- Sarah R. Losso
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
| | - Pauline Affatato
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
| | - Karma Nanglu
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
| | - Javier Ortega-Hernández
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138, USA
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4
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Hou JB, Hughes NC, Hopkins MJ, Shu D. Gill function in an early arthropod and the widespread adoption of the countercurrent exchange mechanism. ROYAL SOCIETY OPEN SCIENCE 2023; 10:230341. [PMID: 37593708 PMCID: PMC10427831 DOI: 10.1098/rsos.230341] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/19/2023] [Accepted: 07/25/2023] [Indexed: 08/19/2023]
Abstract
Rising but fluctuating oxygen levels in the Early Palaeozoic provide an environmental context for the radiation of early metazoans, but little is known about how mechanistically early animals satisfied their oxygen requirements. Here we propose that the countercurrent gaseous exchange, a highly efficient respiratory mechanism, was effective in the gills of the Late Ordovician trilobite Triarthrus eatoni. In order to test this, we use computational fluid dynamics to simulate water flow around its gills and show that water velocity decreased distinctly in front of and between the swollen ends, which first encountered the oxygen-charged water, and slowed continuously at the mid-central region, forming a buffer zone with a slight increase of the water volume. In T. eatoni respiratory surface area was maximized by extending filament height and gill shaft length. In comparison with the oxygen capacity of modern fish and crustaceans, a relatively low weight specific area in T. eatoni may indicate its low oxygen uptake, possibly related to a less active life mode. Exceptionally preserved respiratory structures in the Cambrian deuterostome Haikouella are also consistent with a model of countercurrent gaseous exchange, exemplifying the wide adoption of this strategy among early animals.
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Affiliation(s)
- Jin-Bo Hou
- State Key Laboratory for Mineral Deposits Research, School of Earth Sciences and Engineering and Frontiers Science Center for Critical Earth Material Cycling, Nanjing University, Nanjing 210023, People's Republic of China
- Department of Earth and Planetary Sciences, University of California, Riverside, CA 92521, USA
| | - Nigel C. Hughes
- Department of Earth and Planetary Sciences, University of California, Riverside, CA 92521, USA
| | - Melanie J. Hopkins
- Division of Paleontology (Invertebrates), American Museum of Natural History, New York, NY 10024, USA
| | - Degan Shu
- Early Life Institute and State Key Laboratory of Continental Dynamics, Northwest University, Xi'an 710069, People's Republic of China
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5
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Esteve J, Hughes NC. Developmental and functional controls on enrolment in an ancient, extinct arthropod. Proc Biol Sci 2023; 290:20230871. [PMID: 37312547 PMCID: PMC10265026 DOI: 10.1098/rspb.2023.0871] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Accepted: 05/19/2023] [Indexed: 06/15/2023] Open
Abstract
Three-dimensional models reveal how the mechanics of exoskeletal enrolment changed during the development of a model organism for insights into ancient arthropod development, the 429-million-year-old trilobite Aulacopleura koninckii. Changes in the number, size and allocation of segments within the trunk, coupled with the need to maintain effective exoskeletal shielding of soft tissue during enrolment, necessitated a transition in enrolment style about the onset of mature growth. During an earlier growth phase, enrolment was sphaeroidal, with the venter of the trunk fitting exactly against that of the head. In later growth, if lateral exoskeletal encapsulation was to be maintained trunk length proportions did not permit such exact fitting, requiring an alternative, non-sphaeoridal enrolment style. Our study favours the adoption of a posture in later growth in which the posterior trunk extended beyond the front of the head. This change in enrolment accommodated a pattern of notable variation in the number of mature trunk segments, well known to characterize the development of this species. It suggests how an animal whose early segmental development was remarkably precisely controlled was able to realize the marked variation in mature segment number that was related, apparently, to life in a physically challenging, reduced oxygen setting.
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Affiliation(s)
- Jorge Esteve
- Departamento de Geodinámica, Estratigrafía y Paleontología, Facultad de CC. Geológicas, UniversidadComplutense de Madrid, 28040, Madrid, Spain
| | - Nigel C. Hughes
- Department of Earth and Planetary Sciences, University of California, Riverside, CA 92521, USA
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Tihelka E, Howard RJ, Cai C, Lozano-Fernandez J. Was There a Cambrian Explosion on Land? The Case of Arthropod Terrestrialization. BIOLOGY 2022; 11:biology11101516. [PMID: 36290419 PMCID: PMC9598930 DOI: 10.3390/biology11101516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Revised: 10/06/2022] [Accepted: 10/14/2022] [Indexed: 01/24/2023]
Abstract
Arthropods, the most diverse form of macroscopic life in the history of the Earth, originated in the sea. Since the early Cambrian, at least ~518 million years ago, these animals have dominated the oceans of the world. By the Silurian-Devonian, the fossil record attests to arthropods becoming the first animals to colonize land, However, a growing body of molecular dating and palaeontological evidence suggests that the three major terrestrial arthropod groups (myriapods, hexapods, and arachnids), as well as vascular plants, may have invaded land as early as the Cambrian-Ordovician. These dates precede the oldest fossil evidence of those groups and suggest an unrecorded continental "Cambrian explosion" a hundred million years prior to the formation of early complex terrestrial ecosystems in the Silurian-Devonian. We review the palaeontological, phylogenomic, and molecular clock evidence pertaining to the proposed Cambrian terrestrialization of the arthropods. We argue that despite the challenges posed by incomplete preservation and the scarcity of early Palaeozoic terrestrial deposits, the discrepancy between molecular clock estimates and the fossil record is narrower than is often claimed. We discuss strategies for closing the gap between molecular clock estimates and fossil data in the evolution of early ecosystems on land.
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Affiliation(s)
- Erik Tihelka
- School of Earth and Biological Sciences, University of Bristol, Bristol BS8 1TQ, UK
| | - Richard J. Howard
- Department of Earth Sciences, The Natural History Museum, London SW7 5BD, UK
| | - Chenyang Cai
- School of Earth and Biological Sciences, University of Bristol, Bristol BS8 1TQ, UK
- State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, and Center for Excellence in Life and Paleoenvironment, Chinese Academy of Sciences, Nanjing 210008, China
| | - Jesus Lozano-Fernandez
- School of Earth and Biological Sciences, University of Bristol, Bristol BS8 1TQ, UK
- Department of Genetics, Microbiology and Statistics & Biodiversity Research Institute (IRBio), University of Barcelona, 08028 Barcelona, Spain
- Correspondence:
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7
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Schmidt M, Hou X, Zhai D, Mai H, Belojević J, Chen X, Melzer RR, Ortega-Hernández J, Liu Y. Before trilobite legs: Pygmaclypeatus daziensis reconsidered and the ancestral appendicular organization of Cambrian artiopods. Philos Trans R Soc Lond B Biol Sci 2022; 377:20210030. [PMID: 35125003 PMCID: PMC8819370 DOI: 10.1098/rstb.2021.0030] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The Cambrian Stage 3 Chengjiang biota in South China is one of the most influential Konservat-Lagerstätten worldwide thanks to the fossilization of diverse non-biomineralizing organisms through pyritization. Despite their contributions to understanding the evolution of early animals, several Chengjiang species remain poorly known owing 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. Pygmaclypeatus 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, endopodite and exopodite along with the antero-posterior body axis. The small body size (less than 2 cm), the presence of delicate spinose endites and well-developed exopodites with multiple paddle-shaped lamellae on the appendages of P. daziensis indicate a nekto-benthic mode of life and a scavenging/detritus feeding strategy. Pygmaclypeatus daziensis shows that appendage heteronomy is phylogenetically widespread within Artiopoda-the megadiverse clade that includes trilobites and their relatives with non-biomineralizing exoskeletons-and suggests that a single exopodite lobe with paddle-like lamellae is ancestral for this clade. This article is part of the theme issue 'The impact of Chinese palaeontology on evolutionary research'.
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Affiliation(s)
- Michel Schmidt
- MEC International Joint Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, North Cuihu Road 2, Kunming 650091, People's Republic of China.,Bavarian State Collection of Zoology, Bavarian Natural History Collections, Münchhausenstrasse 21, 81247 München, Germany.,Department Biology II, Ludwig-Maximilians-Universität München, 82152 Planegg-Martinsried, Germany
| | - Xianguang Hou
- MEC International Joint Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, North Cuihu Road 2, Kunming 650091, People's Republic of China.,Yunnan Key Laboratory for Palaeobiology, Institute of Palaeontology, Yunnan University, North Cuihu Road 2, Kunming 650091, People's Republic of China
| | - Dayou Zhai
- MEC International Joint Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, North Cuihu Road 2, Kunming 650091, People's Republic of China.,Yunnan Key Laboratory for Palaeobiology, Institute of Palaeontology, Yunnan University, North Cuihu Road 2, Kunming 650091, People's Republic of China
| | - Huijuan Mai
- MEC International Joint Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, North Cuihu Road 2, Kunming 650091, People's Republic of China.,Yunnan Key Laboratory for Palaeobiology, Institute of Palaeontology, Yunnan University, North Cuihu Road 2, Kunming 650091, People's Republic of China
| | - Jelena Belojević
- Bavarian State Collection of Zoology, Bavarian Natural History Collections, Münchhausenstrasse 21, 81247 München, Germany
| | - Xiaohan Chen
- MEC International Joint Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, North Cuihu Road 2, Kunming 650091, People's Republic of China.,Yunnan Key Laboratory for Palaeobiology, Institute of Palaeontology, Yunnan University, North Cuihu Road 2, Kunming 650091, People's Republic of China
| | - Roland R Melzer
- MEC International Joint Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, North Cuihu Road 2, Kunming 650091, People's Republic of China.,Bavarian State Collection of Zoology, Bavarian Natural History Collections, Münchhausenstrasse 21, 81247 München, Germany.,Department Biology II, Ludwig-Maximilians-Universität München, 82152 Planegg-Martinsried, Germany.,GeoBio-Center, Ludwig-Maximilians-Universität Munich, Luisenstrasse 37, 80333 München, Germany
| | - Javier Ortega-Hernández
- Museum of Comparative Zoology and Department of Organismic and Evolutionary Biology, Harvard University, 26 Oxford Street, 791 Cambridge, MA 02138, USA
| | - Yu Liu
- MEC International Joint Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, North Cuihu Road 2, Kunming 650091, People's Republic of China.,Yunnan Key Laboratory for Palaeobiology, Institute of Palaeontology, Yunnan University, North Cuihu Road 2, Kunming 650091, People's Republic of China
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8
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Fu D, Legg DA, Daley AC, Budd GE, Wu Y, Zhang X. The evolution of biramous appendages revealed by a carapace-bearing Cambrian arthropod. Philos Trans R Soc Lond B Biol Sci 2022; 377:20210034. [PMID: 35125000 PMCID: PMC8819368 DOI: 10.1098/rstb.2021.0034] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Biramous appendages are a common feature among modern marine arthropods that evolved deep in arthropod phylogeny. The branched appendage of Cambrian arthropods has long been considered as the ancient biramous limb, sparking numerous investigations on its origin and evolution. Here, we report a new arthropod, Erratus sperare gen. et sp. nov., from the Lower Cambrian (Stage 3, 520 Ma) Chengjiang biota of Yunnan, China, with unique trunk appendages formed of lateral anomalocaridid-type flaps and ventral subconical endopods. These appendages represent an intermediate stage of biramous limb evolution, i.e. from 'two pairs of flap appendages' in radiodonts to 'flap + endopod' in Erratus, to 'exopod + endopod' in the rest of carapace-bearing arthropods that populate the basal region of the upper-stem lineage arthropods (deuteropods). The new species occupies a phylogenetic position at the first node closer to deuteropods than to radiodonts, and therefore pinpoints the earliest occurrence of the endopod within Deuteropoda. The primitive endopod is weakly sclerotized, and has unspecialized segments without endites or claw. The findings might support previous claims that the outer branch of the biramous limb of fossil marine arthropods, such as trilobites, is not a true exopod, but is instead a modified exite. This article is part of the theme issue 'The impact of Chinese palaeontology on evolutionary research'.
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Affiliation(s)
- Dongjing Fu
- State Key Laboratory of Continental Dynamics, Shaanxi Key Laboratory of Early Life and Environments, Department of Geology, Northwest University, Xian 710069, People's Republic of China
| | - David A Legg
- Department of Earth, Atmospheric, and Environmental Sciences, University of Manchester, Manchester, UK
| | - Allison C Daley
- Institute of Earth Sciences, University of Lausanne, Geopolis, Lausanne 1015, Switzerland
| | - Graham E Budd
- Department of Earth Sciences, Palaeobiology, Uppsala University, Villavägen 16, Uppsala 752 36, Sweden
| | - Yu Wu
- State Key Laboratory of Continental Dynamics, Shaanxi Key Laboratory of Early Life and Environments, Department of Geology, Northwest University, Xian 710069, People's Republic of China
| | - Xingliang Zhang
- State Key Laboratory of Continental Dynamics, Shaanxi Key Laboratory of Early Life and Environments, Department of Geology, Northwest University, Xian 710069, People's Republic of China
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9
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Liu Y, Edgecombe GD, Schmidt M, Bond AD, Melzer RR, Zhai D, Mai H, Zhang M, Hou X. Exites in Cambrian arthropods and homology of arthropod limb branches. Nat Commun 2021; 12:4619. [PMID: 34330912 PMCID: PMC8324779 DOI: 10.1038/s41467-021-24918-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Accepted: 07/14/2021] [Indexed: 11/28/2022] Open
Abstract
The last common ancestor of all living arthropods had biramous postantennal appendages, with an endopodite and exopodite branching off the limb base. Morphological evidence for homology of these rami between crustaceans and chelicerates has, however, been challenged by data from clonal composition and from knockout of leg patterning genes. Cambrian arthropod fossils have been cited as providing support for competing hypotheses about biramy but have shed little light on additional lateral outgrowths, known as exites. Here we draw on microtomographic imaging of the Cambrian great-appendage arthropod Leanchoilia to reveal a previously undetected exite at the base of most appendages, composed of overlapping lamellae. A morphologically similar, and we infer homologous, exite is documented in the same position in members of the trilobite-allied Artiopoda. This early Cambrian exite morphology supplements an emerging picture from gene expression that exites may have a deeper origin in arthropod phylogeny than has been appreciated.
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Affiliation(s)
- Yu Liu
- Yunnan Key Laboratory for Palaeobiology, Institute of Palaeontology, Yunnan University, Kunming, China
- MEC International Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, Kunming, China
| | - Gregory D Edgecombe
- MEC International Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, Kunming, China.
- Department of Earth Sciences, The Natural History Museum, London, UK.
| | - Michel Schmidt
- MEC International Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, Kunming, China
- Bavarian State Collection of Zoology, Bavarian Natural History Collections, München, Germany
- Department Biology II, Ludwig-Maximilians-Universität München, Planegg-Martinsried, München, Germany
| | - Andrew D Bond
- Department of Earth Sciences, Royal Holloway University of London, Egham, Surrey, UK
| | - Roland R Melzer
- MEC International Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, Kunming, China
- Bavarian State Collection of Zoology, Bavarian Natural History Collections, München, Germany
- Department Biology II, Ludwig-Maximilians-Universität München, Planegg-Martinsried, München, Germany
- GeoBio-Center, Ludwig-Maximilians-Universität München, München, Germany
| | - Dayou Zhai
- Yunnan Key Laboratory for Palaeobiology, Institute of Palaeontology, Yunnan University, Kunming, China
- MEC International Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, Kunming, China
| | - Huijuan Mai
- Yunnan Key Laboratory for Palaeobiology, Institute of Palaeontology, Yunnan University, Kunming, China
- MEC International Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, Kunming, China
| | - Maoyin Zhang
- Yunnan Key Laboratory for Palaeobiology, Institute of Palaeontology, Yunnan University, Kunming, China
- MEC International Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, Kunming, China
| | - Xianguang Hou
- Yunnan Key Laboratory for Palaeobiology, Institute of Palaeontology, Yunnan University, Kunming, China.
- MEC International Laboratory for Palaeobiology and Palaeoenvironment, Yunnan University, Kunming, China.
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