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Klug C, Spiekman SNF, Bastiaans D, Scheffold B, Scheyer TM. The marine conservation deposits of Monte San Giorgio (Switzerland, Italy): the prototype of Triassic black shale Lagerstätten. SWISS JOURNAL OF PALAEONTOLOGY 2024; 143:11. [PMID: 38450287 PMCID: PMC10912274 DOI: 10.1186/s13358-024-00308-7] [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: 08/21/2023] [Accepted: 01/23/2024] [Indexed: 03/08/2024]
Abstract
Marine conservation deposits ('Konservat-Lagerstätten') are characterized by their mode of fossil preservation, faunal composition and sedimentary facies. Here, we review these characteristics with respect to the famous conservation deposit of the Besano Formation (formerly Grenzbitumenzone; including the Anisian-Ladinian boundary), and the successively younger fossil-bearing units Cava inferiore, Cava superiore, Cassina beds and the Kalkschieferzone of Monte San Giorgio (Switzerland and Italy). We compare these units to a selection of important black shale-type Lagerstätten of the global Phanerozoic plus the Ediacaran in order to detect commonalities in their facies, genesis, and fossil content using principal component and hierarchical cluster analyses. Further, we put the Monte San Giorgio type Fossillagerstätten into the context of other comparable Triassic deposits worldwide based on their fossil content. The results of the principal component and cluster analyses allow a subdivision of the 45 analysed Lagerstätten into four groups, for which we suggest the use of the corresponding pioneering localities: Burgess type for the early Palaeozoic black shales, Monte San Giorgio type for the Triassic black shales, Holzmaden type for the pyrite-rich black shales and Solnhofen type for platy limestones.
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Affiliation(s)
- Christian Klug
- Universität Zürich, Paläontologisches Institut, Karl-Schmid-Strasse 4, 8006 Zurich, Switzerland
| | | | - Dylan Bastiaans
- Universität Zürich, Paläontologisches Institut, Karl-Schmid-Strasse 4, 8006 Zurich, Switzerland
| | - Beat Scheffold
- Universität Zürich, Paläontologisches Institut, Karl-Schmid-Strasse 4, 8006 Zurich, Switzerland
| | - Torsten M. Scheyer
- Universität Zürich, Paläontologisches Institut, Karl-Schmid-Strasse 4, 8006 Zurich, Switzerland
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Klein N, Sander PM, Liu J, Druckenmiller P, Metz ET, Kelley NP, Scheyer TM. Comparative bone histology of two thalattosaurians (Diapsida: Thalattosauria): Askeptosaurus italicus from the Alpine Triassic (Middle Triassic) and a Thalattosauroidea indet. from the Carnian of Oregon (Late Triassic). SWISS JOURNAL OF PALAEONTOLOGY 2023; 142:15. [PMID: 37601161 PMCID: PMC10432342 DOI: 10.1186/s13358-023-00277-3] [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: 04/25/2023] [Accepted: 05/30/2023] [Indexed: 08/22/2023]
Abstract
Here, we present the first bone histological and microanatomical study of thalattosaurians, an enigmatic group among Triassic marine reptiles. Two taxa of thalattosaurians, the askeptosauroid Askeptosaurus italicus and one as yet undescribed thalattosauroid, are examined. Both taxa have a rather different microanatomy, tissue type, and growth pattern. Askeptosaurus italicus from the late Anisian middle Besano Formation of the southern Alpine Triassic shows very compact tissue in vertebrae, rib, a gastralium, and femora, and all bones are without medullary cavities. The tissue shows moderate to low vascularization, dominated by highly organized and very coarse parallel-fibred bone, resembling interwoven tissue. Vascularization is dominated by simple longitudinal vascular canals, except for the larger femur of Askeptosaurus, where simple vascular canals dominate in a radial arrangement. Growth marks stratify the cortex of femora. The vertebrae and humeri from the undescribed thalattosauroid from the late Carnian of Oregon have primary and secondary cancellous bone, resulting in an overall low bone compactness. Two dorsal vertebral centra show dominantly secondary trabeculae, whereas a caudal vertebral centrum shows much primary trabecular bone, globuli ossei, and cartilage, indicating an earlier ontogenetic stage of the specimens or paedomorphosis. The humeri of the thalattosauroid show large, simple vascular canals that are dominantly radially oriented in a scaffold of woven and loosely organized parallel-fibred tissue. Few of the simple vascular canals are thinly but only incompletely lined by parallel-fibered tissue. In the Oregon material, changes in growth rate are only indicated by changes in vascular organization but no distinct growth marks were identified. The compact bone of Askeptosaurus is best comparable to some pachypleurosaurs, whereas its combination of tissue and vascularity is similar to eosauropterygians in general, except for the coarse nature of its parallel-fibred tissue. The cancellous bone of the Oregon thalattosauroid resembles what is documented in ichthyosaurs and plesiosaurs. However, in contrast to these its tissue does not consist of fibro-lamellar bone type. Tissue types of both thalattosaurian taxa indicate rather different growth rates and growth patterns, associated with different life history strategies. The microanatomy reflects different life styles that fit to the different environments in which they had been found (intraplatform basin vs. open marine). Both thalattosaurian taxa differ from each other but in sum also from all other marine reptile taxa studied so far. Thalattosaurian bone histology documents once more that bone histology provides for certain groups (i.e., Triassic Diapsida) only a poor phylogenetic signal and is more influenced by exogenous factors. Differences in lifestyle, life history traits, and growth rate and pattern enabled all these Triassic marine reptiles to live contemporaneously in the same habitat managing to avoid substantial competition.
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Affiliation(s)
- N. Klein
- Department of Palaeontology, University of Zurich, Karl Schmid-Strasse 4, 8006 Zurich, Switzerland
- Department of Palaeontology, Institute of Geosciences, University of Bonn, Nußallee 8, 53115 Bonn, Germany
| | - P. M. Sander
- Department of Palaeontology, Institute of Geosciences, University of Bonn, Nußallee 8, 53115 Bonn, Germany
- School of Resources and Environmental Engineering, Hefei University of Technology, 193 Tunxi Road, Hefei, 230009 China
| | - J. Liu
- School of Resources and Environmental Engineering, Hefei University of Technology, 193 Tunxi Road, Hefei, 230009 China
| | - P. Druckenmiller
- University of Alaska Museum, 1962 Yukon Dr., Fairbanks, AK 99775 USA
- Department of Geosciences, University of Alaska Fairbanks, 1930 Yukon Dr., Fairbanks, AK 99775 USA
| | - E. T. Metz
- Museum of the Rockies, Montana State University, 600 W Kagy Blvd., Bozeman, MT 59717 USA
| | - N. P. Kelley
- Department of Earth and Environmental Sciences, Vanderbilt University, Nashville, TN 37240 USA
| | - T. M. Scheyer
- Department of Palaeontology, University of Zurich, Karl Schmid-Strasse 4, 8006 Zurich, Switzerland
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Wolniewicz AS, Shen Y, Li Q, Sun Y, Qiao Y, Chen Y, Hu YW, Liu J. An armoured marine reptile from the Early Triassic of South China and its phylogenetic and evolutionary implications. eLife 2023; 12:e83163. [PMID: 37551884 PMCID: PMC10499374 DOI: 10.7554/elife.83163] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Accepted: 08/07/2023] [Indexed: 08/09/2023] Open
Abstract
Sauropterygia was a taxonomically and ecomorphologically diverse clade of Mesozoic marine reptiles spanning the Early Triassic to the Late Cretaceous. Sauropterygians are traditionally divided into two groups representing two markedly different body plans - the short-necked, durophagous Placodontia and the long-necked Eosauropterygia - whereas Saurosphargidae, a small clade of armoured marine reptiles, is generally considered as the sauropterygian sister-group. However, the early evolutionary history of sauropterygians and their phylogenetic relationships with other groups within Diapsida are still incompletely understood. Here, we report a new saurosphargid from the Early Triassic (Olenekian) of South China - Prosaurosphargis yingzishanensis gen. et sp. nov. - representing the earliest known occurrence of the clade. An updated phylogenetic analysis focussing on the interrelationships among diapsid reptiles recovers saurosphargids as nested within sauropterygians, forming a clade with eosauropterygians to the exclusion of placodonts. Furthermore, a clade comprising Eusaurosphargis and Palatodonta is recovered as the sauropterygian sister-group within Sauropterygomorpha tax. nov. The phylogenetic position of several Early and Middle Triassic sauropterygians of previously uncertain phylogenetic affinity, such as Atopodentatus, Hanosaurus, Majiashanosaurus, and Corosaurus, is also clarified, elucidating the early evolutionary assembly of the sauropterygian body plan. Finally, our phylogenetic analysis supports the placement of Testudines and Archosauromorpha within Archelosauria, a result strongly corroborated by molecular data, but only recently recovered in a phylogenetic analysis using a morphology-only dataset. Our study provides evidence for the rapid diversification of sauropterygians in the aftermath of the Permo-Triassic mass extinction event and emphasises the importance of broad taxonomic sampling in reconstructing phylogenetic relationships among extinct taxa.
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Affiliation(s)
- Andrzej S Wolniewicz
- School of Resources and Environmental Engineering, Hefei University of TechnologyHefeiChina
- Institute of Paleobiology, Polish Academy of SciencesWarsawPoland
| | - Yuefeng Shen
- School of Resources and Environmental Engineering, Hefei University of TechnologyHefeiChina
| | - Qiang Li
- School of Resources and Environmental Engineering, Hefei University of TechnologyHefeiChina
- Section Paleontology, Institute of Geosciences, University of BonnBonnGermany
| | - Yuanyuan Sun
- Chengdu Center, China Geological Survey (Southwest China Innovation Center for Geosciences)ChengduChina
| | - Yu Qiao
- School of Resources and Environmental Engineering, Hefei University of TechnologyHefeiChina
| | - Yajie Chen
- School of Resources and Environmental Engineering, Hefei University of TechnologyHefeiChina
| | - Yi-Wei Hu
- School of Resources and Environmental Engineering, Hefei University of TechnologyHefeiChina
| | - Jun Liu
- School of Resources and Environmental Engineering, Hefei University of TechnologyHefeiChina
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Jiang B, He Y, Elsler A, Wang S, Keating JN, Song J, Kearns SL, Benton MJ. Extended embryo retention and viviparity in the first amniotes. Nat Ecol Evol 2023; 7:1131-1140. [PMID: 37308704 PMCID: PMC10333127 DOI: 10.1038/s41559-023-02074-0] [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: 11/04/2022] [Accepted: 04/17/2023] [Indexed: 06/14/2023]
Abstract
The amniotic egg with its complex fetal membranes was a key innovation in vertebrate evolution that enabled the great diversification of reptiles, birds and mammals. It is debated whether these fetal membranes evolved in eggs on land as an adaptation to the terrestrial environment or to control antagonistic fetal-maternal interaction in association with extended embryo retention (EER). Here we report an oviparous choristodere from the Lower Cretaceous period of northeast China. The ossification sequence of the embryo confirms that choristoderes are basal archosauromorphs. The discovery of oviparity in this assumed viviparous extinct clade, together with existing evidence, suggests that EER was the primitive reproductive mode in basal archosauromorphs. Phylogenetic comparative analyses on extant and extinct amniotes suggest that the first amniote displayed EER (including viviparity).
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Affiliation(s)
- Baoyu Jiang
- 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, China.
| | - Yiming He
- 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, China
| | - Armin Elsler
- School of Earth Sciences, Life Sciences Building, Tyndall Avenue, University of Bristol, Bristol, UK
| | - Shengyu Wang
- 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, China
| | - Joseph N Keating
- 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, China
| | - Junyi Song
- 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, China
| | - Stuart L Kearns
- School of Earth Sciences, Life Sciences Building, Tyndall Avenue, University of Bristol, Bristol, UK
| | - Michael J Benton
- School of Earth Sciences, Life Sciences Building, Tyndall Avenue, University of Bristol, Bristol, UK
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Qiao Y, Liu J, Wolniewicz AS, Iijima M, Shen Y, Wintrich T, Li Q, Sander PM. A globally distributed durophagous marine reptile clade supports the rapid recovery of pelagic ecosystems after the Permo-Triassic mass extinction. Commun Biol 2022; 5:1242. [PMCID: PMC9663502 DOI: 10.1038/s42003-022-04162-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2022] [Accepted: 10/24/2022] [Indexed: 11/16/2022] Open
Abstract
AbstractMarine ecosystem recovery after the Permo-Triassic mass extinction (PTME) has been extensively studied in the shallow sea, but little is known about the nature of this process in pelagic ecosystems. Omphalosauridae, an enigmatic clade of open-water durophagous marine reptiles, potentially played an important role in the recovery, but their fragmentary fossils and uncertain phylogenetic position have hindered our understanding of their role in the process. Here we report the large basal ichthyosauriform Sclerocormus from the Early Triassic of China that clearly demonstrates an omphalosaurid affinity, allowing for the synonymy of the recently erected Nasorostra with Omphalosauridae. The skull also reveals the anatomy of the unique feeding apparatus of omphalosaurids, likely an adaptation for feeding on hard-shelled pelagic invertebrates, especially ammonoids. Morphofunctional analysis of jaws shows that omphalosaurids occupy the morphospace of marine turtles. Our discovery adds another piece of evidence for an explosive radiation of marine reptiles into the ocean in the Early Triassic and the rapid recovery of pelagic ecosystems after the PTME.
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Cheng L, C. Moon B, Yan C, Motani R, Jiang D, An Z, Fang Z. The oldest record of Saurosphargiformes (Diapsida) from South China could fill an ecological gap in the Early Triassic biotic recovery. PeerJ 2022; 10:e13569. [PMID: 35855428 PMCID: PMC9288826 DOI: 10.7717/peerj.13569] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Accepted: 05/20/2022] [Indexed: 01/17/2023] Open
Abstract
Diversification following the end-Permian mass extinction marks the initiation of Mesozoic reptile dominance and of modern marine ecosystems, yet major clades are best known from the Middle Triassic suggesting delayed recovery, while Early Triassic localities produce poorly preserved specimens or have restricted diversity. Here we describe Pomolispondylus biani gen. et sp. nov. from the Early Triassic Nanzhang-Yuan'an Fauna of China assigned to Saurosphargiformes tax. nov., a clade known only from the Middle Triassic or later, which includes Saurosphargidae, and likely is the sister taxon to Sauropterygia. Pomolispondylus biani is allied to Saurosphargidae by the extended transverse processes of dorsal vertebrae and a low, table-like dorsal surface on the neural spine; however, it does not have the typical extensive osteoderms. Rather an unusual tuberous texture on the dorsal neural spine and rudimentary ossifications lateral to the gastralia are observed. Discovery of Pomolispondylus biani extends the known range of Saurosphargiformes and increases the taxic and ecological diversity of the Nanzhang-Yuan'an Fauna. Its small size fills a different ecological niche with respect to previously found species, but the overall food web remains notably different in structure to Middle Triassic and later ecosystems, suggesting this fauna represents a transitional stage during recovery rather than its endpoint.
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Affiliation(s)
- Long Cheng
- Hubei Key Laboratory of Paleontology and Geological Environment Evolution, Wuhan Center of China Geological Survey, Wuhan, P. R. China
| | - Benjamin C. Moon
- Palaeobiology Research Group, School of Earth Sciences, University of Bristol, Bristol, UK
| | - Chunbo Yan
- Hubei Key Laboratory of Paleontology and Geological Environment Evolution, Wuhan Center of China Geological Survey, Wuhan, P. R. China
| | - Ryosuke Motani
- University of California Davis, Department of Earth and Planetary Sciences, Davis, California, United States of America
| | - Dayong Jiang
- Peking University, Department of Geology and Geological Museum, Beijing, P. R. China
| | - Zhihui An
- Hubei Key Laboratory of Paleontology and Geological Environment Evolution, Wuhan Center of China Geological Survey, Wuhan, P. R. China
| | - Zichen Fang
- China University of Geoscience, Wuhan, P. R. China
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Klein N, Furrer H, Ehrbar I, Torres Ladeira M, Richter H, Scheyer TM. A new pachypleurosaur from the Early Ladinian Prosanto Formation in the Eastern Alps of Switzerland. SWISS JOURNAL OF PALAEONTOLOGY 2022; 141:12. [PMID: 35844249 PMCID: PMC9276568 DOI: 10.1186/s13358-022-00254-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Accepted: 05/26/2022] [Indexed: 06/15/2023]
Abstract
UNLABELLED The Alpine Prosanto Formation (Middle Triassic) cropping out in the Ducan region in eastern Switzerland has yielded a rich fish and reptile fauna. Here, we present new pachypleurosaur remains from the upper part of the formation (Early Ladinian), similar to the previously known pachypleurosaurs from the Middle Triassic UNESCO World Heritage Site of Monte San Giorgio in southern Switzerland/northern Italy. From these remains, a new pachypleurosaur species, Prosantosaurus scheffoldi nov. gen. et spec., is described on the basis of six fairly complete skeletons, one disarticulated specimen and an isolated skull. As is typical for pachypleurosaurs and most other Triassic marine reptiles, the new taxon is based to a large degree on a combination of characters (e.g., nasals articulating broadly with the anterior margins of the prefrontals and lacking posterior processes; postorbitals with rounded anterior processes that articulate with the postfrontals anterolaterally) rather than on many unambiguous autapomorphies, although a few of the latter were found including (1) a premaxilla which is excluded from entering both the external and internal nares and (2) a parietal, which is distinctly longer than wide and carrying distinct anterolaterally angled processes. Phylogenetic relationships of the new taxon are tested within European Pachypleurosauria, revealing that the new species is the sister taxon to a clade including Serpianosaurus, Proneusticosaurus, and the monophyletic Neusticosaurus spp. Mapping of palaeogeographic and stratigraphical distribution of valid European pachypleurosaurs shows that a formerly proposed scenario of migration of pachypleurosaurs from the eastern Palaeotethys during the Olenekian into the Germanic Basin and a subsequent diversification and invasion during the Anisian into the intraplatform basins of the South Alpine realm must be re-assessed. The exceptional preservation and preparation of the Ducan fossils further allow the description of tooth replacement patterns for the first time in a European pachypleurosaur species. The "alveolarization" of replacement teeth, the horizontal replacement pattern, and the subsequent remodelling of the functional alveoli during tooth replacement supports the monophyly of Sauropterygia as discussed before. SUPPLEMENTARY INFORMATION The online version contains supplementary material available at 10.1186/s13358-022-00254-2.
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Affiliation(s)
- Nicole Klein
- Palaeontological Institute and Museum, University of Zurich, Karl Schmid-Strasse 4, CH-8006 Zurich, Switzerland
| | - Heinz Furrer
- Palaeontological Institute and Museum, University of Zurich, Karl Schmid-Strasse 4, CH-8006 Zurich, Switzerland
| | - Iris Ehrbar
- Palaeontological Institute and Museum, University of Zurich, Karl Schmid-Strasse 4, CH-8006 Zurich, Switzerland
| | - Marta Torres Ladeira
- Palaeontological Institute and Museum, University of Zurich, Karl Schmid-Strasse 4, CH-8006 Zurich, Switzerland
| | - Henning Richter
- Diagnostic Imaging Research Unit (DIRU), Clinic for Diagnostic Imaging, Department of Clinical Diagnostics and Services, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 258c, CH-8057 Zurich, Switzerland
| | - Torsten M. Scheyer
- Palaeontological Institute and Museum, University of Zurich, Karl Schmid-Strasse 4, CH-8006 Zurich, Switzerland
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Scheyer TM, Oberli U, Klein N, Furrer H. A large osteoderm-bearing rib from the Upper Triassic Kössen Formation (Norian/Rhaetian) of eastern Switzerland. SWISS JOURNAL OF PALAEONTOLOGY 2022; 141:1. [PMID: 35250843 PMCID: PMC8866377 DOI: 10.1186/s13358-022-00244-4] [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: 11/01/2021] [Accepted: 01/21/2022] [Indexed: 06/14/2023]
Abstract
An important component of the Alpine vertebrate record of Late Triassic age derives from the Kössen Formation, which crops out extensively in the eastern Alps. Here, we present an isolated and only partially preserved large rib, which carries an osteoderm on a low uncinate process. Osteological comparison indicates that the specimen likely belongs to a small clade of marine reptiles, Saurosphargidae. Members of the clade are restricted to the western (today Europe) and eastern margins of the Tethys (today China) and were so far known only from the Anisian stage of the Middle Triassic. The assignment of the new find to cf. Saurosphargidae, with potential affinities to the genus Largocephalosaurus from the Guanling Formation of Yunnan and Guizhou Provinces, China, would extend the occurrence of the clade about 35 million years into the Late Triassic.
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Affiliation(s)
- Torsten M. Scheyer
- Universität Zürich, Paläontologisches Institut und Museum, Karl Schmid-Strasse 4, CH-8006 Zürich, Switzerland
| | - Urs Oberli
- Waldgutstrasse 21, CH-9010 St.Gallen, Switzerland
| | - Nicole Klein
- Universität Zürich, Paläontologisches Institut und Museum, Karl Schmid-Strasse 4, CH-8006 Zürich, Switzerland
| | - Heinz Furrer
- Universität Zürich, Paläontologisches Institut und Museum, Karl Schmid-Strasse 4, CH-8006 Zürich, Switzerland
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Dalla Vecchia FM. Heteropelta boboi n. gen., n. sp. an armored archosauriform (Reptilia: Archosauromorpha) from the Middle Triassic of Italy. PeerJ 2021; 9:e12468. [PMID: 34820195 PMCID: PMC8601055 DOI: 10.7717/peerj.12468] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Accepted: 10/19/2021] [Indexed: 01/03/2023] Open
Abstract
Heteropelta boboi is a new archosauriform reptile from the upper Anisian of northeastern Italy represented by a fragment of dorsal armor with a row of neural arches of the dorsal vertebrae. The dorsal armor of the new taxon is composed of two columns of paramedian osteoderms and at least six columns of lateral osteoderms. Unlike other armored archosaurs, the osteoderms are imbricated with the posterior osteoderm overlapping the anterior one. The low neural arches bear small neural spines and long postzygapophyses. The osteoderms of the lateral columns increase in size and change in shape from the most medial to the most lateral columns. Among the Archosauriformes, only the non-archosaur proterochampsians Vancleavea campi, Litorosuchus somnii, and the doswelliids have dorsal armor comprised of more than two columns of osteoderms per side, but the morphology and arrangement of their osteoderms is unlike those of the new Italian taxon. A cladistic analysis of Archosauromorpha positions Heteropelta boboi as either a basal phytosaur or a basal suchian. However, a second cladistic analysis focused on armored archosaurs alternatively positions the new taxon as a basal archosauriform, basal suchian, basal loricatan or crocodylomorph. Better resolution of the phylogenetic relationships of Heteropelta boboi will likely be obtained only with the discovery of cranial and postcranial remains associated with its diagnostic armor elements.
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Affiliation(s)
- Fabio Marco Dalla Vecchia
- Mesozoic Research Group, Institut Català de Paleontologia Miquel Crusafont (ICP), Sabadell, Catalonia, Spain.,Museo Friulano di Storia Naturale, Udine, Italy
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Pritchard AC, Sues HD, Scott D, Reisz RR. Osteology, relationships and functional morphology of Weigeltisaurus jaekeli (Diapsida, Weigeltisauridae) based on a complete skeleton from the Upper Permian Kupferschiefer of Germany. PeerJ 2021; 9:e11413. [PMID: 34055483 PMCID: PMC8141288 DOI: 10.7717/peerj.11413] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Accepted: 04/15/2021] [Indexed: 11/20/2022] Open
Abstract
BACKGROUND Weigeltisauridae is a clade of small-bodied diapsids characterized by a horned cranial frill, slender trunk and limbs, and a patagium supported by elongated bony rods. Partial skeletons and fragments are definitively known only from upper Permian (Lopingian) rocks in England, Germany, Madagascar and Russia. Despite these discoveries, there have been few detailed descriptions of weigeltisaurid skeletons, and the homologies of many skeletal elements-especially the rods supporting the patagium-remain the subject of controversy. MATERIALS & METHODS Here, we provide a detailed description of a nearly complete skeleton of Weigeltisaurus jaekeli from the upper Permian (Lopingian: Wuchiapingian) Kupferschiefer of Lower Saxony, Germany. Briefly addressed by past authors, the skeleton preserves a nearly complete skull, postcranial axial skeleton, appendicular skeleton, and patagial supports. Through comparisons with extant and fossil diapsids, we examine the hypotheses for the homologies of the patagial rods. To examine the phylogenetic position of Weigeltisauridae and characterize the morphology of the clade, we integrate the material and other weigeltisaurids into a parsimony-based phylogenetic analysis focused on Permo-Triassic non-saurian Diapsida and early Sauria (61 taxa, 339 characters). RESULTS We recognize a number of intriguing anatomical features in the weigeltisaurid skeleton described here, including hollow horns on the post-temporal arch, lanceolate teeth in the posterior portion of the maxilla, the absence of a bony arch connecting the postorbital and squamosal bones, elongate and slender phalanges that resemble those of extant arboreal squamates, and patagial rods that are positioned superficial to the lateral one third of the gastral basket. Our phylogenetic study recovers a monophyletic Weigeltisauridae including Coelurosauravus elivensis, Weigeltisaurus jaekeli, and Rautiania spp. The clade is recovered as the sister taxon to Drepanosauromorpha outside of Sauria (=Lepidosauria + Archosauria). CONCLUSIONS Our anatomical observations and phylogenetic analysis show variety of plesiomorphic diapsid characters and apomorphies of Weigeltisauridae in the specimen described here. We corroborate the hypothesis that the patagial ossifications are dermal bones unrelated to the axial skeleton. The gliding apparatus of weigeltisaurids was constructed from dermal elements unknown in other known gliding diapsids. SMNK-PAL 2882 and other weigeltisaurid specimens highlight the high morphological disparity of Paleozoic diapsids already prior to their radiation in the early Mesozoic.
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Affiliation(s)
- Adam C. Pritchard
- Department of Paleontology, Virginia Museum of Natural History, Martinsville, Virginia, United States
- Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington, District of Columbia, United States
| | - Hans-Dieter Sues
- Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington, District of Columbia, United States
| | - Diane Scott
- Department of Biology, University of Toronto Mississauga, Mississauga, Ontario, Canada
| | - Robert R. Reisz
- Department of Biology, University of Toronto Mississauga, Mississauga, Ontario, Canada
- Dinosaur Evolution Research Centre and International Centre of Future Science, Jilin University, Changchun, China
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Sobral G, Simões TR, Schoch RR. A tiny new Middle Triassic stem-lepidosauromorph from Germany: implications for the early evolution of lepidosauromorphs and the Vellberg fauna. Sci Rep 2020; 10:2273. [PMID: 32080209 PMCID: PMC7033234 DOI: 10.1038/s41598-020-58883-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Accepted: 01/22/2020] [Indexed: 11/10/2022] Open
Abstract
The Middle Triassic was a time of major changes in tetrapod faunas worldwide, but the fossil record for this interval is largely obscure for terrestrial faunas. This poses a severe limitation to our understanding on the earliest stages of diversification of lineages representing some of the most diverse faunas in the world today, such as lepidosauromorphs (e.g., lizards and tuataras). Here, we report a tiny new lepidosauromorph from the Middle Triassic from Vellberg (Germany), which combines a mosaic of features from both early evolving squamates and rhynchocephalians, such as the simultaneous occurrence of a splenial bone and partial development of acrodonty. Phylogenetic analyses applying different optimality criteria, and combined morphological and molecular data, consistently recover the new taxon as a stem-lepidosauromorph, implying stem-lepidosauromorph species coinhabited areas comprising today's central Europe at the same time as the earliest known rhynchocephalians and squamates. It further demonstrates a more complex evolutionary scenario for dental evolution in early lepidosauromorphs, with independent acquisitions of acrodonty early in their evolutionary history. The small size of most terrestrial vertebrates from Vellberg is conspicuous, contrasting to younger Triassic deposits worldwide, but comparable to Early Triassic faunas, suggesting a potential long-lasting Lilliput effect in this fauna.
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Affiliation(s)
- Gabriela Sobral
- Staatliches Museum für Naturkunde Stuttgart, Rosenstein 1, D-70191, Stuttgart, Germany.
| | - Tiago R Simões
- Department of Organismic and Evolutionary Biology, Museum of Comparative Zoology, Harvard University, Cambridge, MA, 02138, USA
| | - Rainer R Schoch
- Staatliches Museum für Naturkunde Stuttgart, Rosenstein 1, D-70191, Stuttgart, Germany
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Wang W, Li C, Wu XC. An adult specimen of Sinocyamodus xinpuensis (Sauropterygia: Placodontia) from Guanling, Guizhou, China. Zool J Linn Soc 2018. [DOI: 10.1093/zoolinnean/zly080] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Affiliation(s)
- Wei Wang
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China
- CAS Center for Excellence in Life and Paleoenvironment, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
- Universität Zürich, Paläontologisches Institut und Museum, Zürich, Switzerland
| | - Chun Li
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China
- CAS Center for Excellence in Life and Paleoenvironment, Beijing, China
| | - Xiao-Chun Wu
- Canadian Museum of Nature, Station D, Ottawa, Ontario, Canada
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Lautenschlager S, Ferreira GS, Werneburg I. Sensory Evolution and Ecology of Early Turtles Revealed by Digital Endocranial Reconstructions. Front Ecol Evol 2018. [DOI: 10.3389/fevo.2018.00007] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
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14
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Scheyer TM, Neenan JM, Bodogan T, Furrer H, Obrist C, Plamondon M. A new, exceptionally preserved juvenile specimen of Eusaurosphargis dalsassoi (Diapsida) and implications for Mesozoic marine diapsid phylogeny. Sci Rep 2017; 7:4406. [PMID: 28667331 PMCID: PMC5493663 DOI: 10.1038/s41598-017-04514-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Accepted: 05/16/2017] [Indexed: 11/17/2022] Open
Abstract
Recently it was suggested that the phylogenetic clustering of Mesozoic marine reptile lineages, such as thalattosaurs, the very successful fish-shaped ichthyosaurs and sauropterygians (including plesiosaurs), among others, in a so-called 'superclade' is an artefact linked to convergent evolution of morphological characters associated with a shared marine lifestyle. Accordingly, partial 'un-scoring' of the problematic phylogenetic characters was proposed. Here we report a new, exceptionally preserved and mostly articulated juvenile skeleton of the diapsid reptile, Eusaurosphargis dalsassoi, a species previously recovered within the marine reptile 'superclade', for which we now provide a revised diagnosis. Using micro-computed tomography, we show that besides having a deep skull with a short and broad rostrum, the most outstanding feature of the new specimen is extensive, complex body armour, mostly preserved in situ, along its vertebrae, ribs, and forelimbs, as well as a row of flat, keeled ventrolateral osteoderms associated with the gastralia. As a whole, the anatomical features support an essentially terrestrial lifestyle of the animal. A review of the proposed partial character 'un-scoring' using three published data matrices indicate that this approach is flawed and should be avoided, and that within the marine reptile 'superclade' E. dalsassoi potentially is the sister taxon of Sauropterygia.
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Affiliation(s)
- Torsten M Scheyer
- Universität Zürich, Paläontologisches Institut und Museum, Karl Schmid-Strasse 4, CH-8006, Zurich, Switzerland.
| | - James M Neenan
- Oxford University Museum of Natural History, Parks Road, Oxford, OX1 3PW, UK
| | - Timea Bodogan
- Universität Zürich, Paläontologisches Institut und Museum, Karl Schmid-Strasse 4, CH-8006, Zurich, Switzerland
| | - Heinz Furrer
- Universität Zürich, Paläontologisches Institut und Museum, Karl Schmid-Strasse 4, CH-8006, Zurich, Switzerland
| | | | - Mathieu Plamondon
- Empa, Swiss Federal Laboratories for Materials Science and Technology, Center for X-ray Analytics, Überlandstrasse 129, CH-8600, Dübendorf, Switzerland
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