An armoured marine reptile from the Early Triassic of South China and its phylogenetic and evolutionary implications
- Hefei University of Technology, China
- China Geological Survey, China
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 Testudinata 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.
Data availability
Specimen HFUT YZSB-19-109 is housed in the collections of the Geological Museum, Hefei University of Technology, Hefei, China and available for examination upon request to J.L. The phylogenetic data matrix used in this study is available in Source Data 1.
Article and author information
Author details
Andrzej S Wolniewicz
Funding
National Natural Science Foundation of China (42172026)
- Jun Liu
National Natural Science Foundation of China (41772003)
- Jun Liu
National Natural Science Foundation of China (42202006)
- Andrzej S Wolniewicz
National Natural Science Foundation of China (41902104)
- Yuefeng Shen
National Natural Science Foundation of China (41807333)
- Yuanyuan Sun
Chengdu Center of China Geological Survey (Liu Baojun Funding)
- Yuanyuan Sun
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2023, Wolniewicz et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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An armoured marine reptile from the Early Triassic of South China and its phylogenetic and evolutionary implications
eLife 12:e83163.
https://doi.org/10.7554/eLife.83163
