Scleromochlus and the early evolution of Pterosauromorpha

Davide Foffa*, Emma Dunne, Sterling J. Nesbitt, Richard Butler, Nicholas Fraser, Stephen Brusatte, Alex Farnsworth, Daniel J. Lunt, Paul J. Valdes, Stig Walsh, Paul M. Barrett

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

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Abstract

Pterosaurs, the first vertebrates to evolve powered flight, were key components of Mesozoic terrestrial ecosystems from their sudden appearance in the Late Triassic until their demise at the end of the Cretaceous. However, the origin and early evolution of pterosaurs are poorly understood owing to a substantial stratigraphic and morphological gap between these reptiles and their closest relatives6, Lagerpetidae. Scleromochlus taylori, a tiny reptile from the early Late Triassic of Scotland discovered over a century ago, was hypothesized to be a key taxon closely related to pterosaurs, but its poor preservation has limited previous studies and resulted in controversy over its phylogenetic position, with some even doubting its identification as an archosaur. Here we use microcomputed tomographic scans to provide the first accurate whole-skeletal reconstruction and a revised diagnosis of Scleromochlus, revealing new anatomical details that conclusively identify it as a close pterosaur relative within Pterosauromorpha (the lagerpetid + pterosaur clade). Scleromochlus is anatomically more similar to lagerpetids than to pterosaurs and retains numerous features that were probably present in very early diverging members of Avemetatarsalia (bird-line archosaurs). These results support the hypothesis that the first flying reptiles evolved from tiny, probably facultatively bipedal, cursorial ancestors.
Original languageEnglish
Pages (from-to)313-318
Number of pages6
JournalNature
Volume610
Issue number7931
Early online date5 Oct 2022
DOIs
Publication statusPublished - 13 Oct 2022

Bibliographical note

Funding Information:
We thank V. Fernandez, T. G. Davies and E. G. Martin-Silverstone for scanning the specimens; A. A. Chiarenza for discussion and assistance; G. Ugueto for creating the artwork that accompanies this paper; M. Humpage for the 3D reconstruction of the skeleton; A. Fitch for sharing the photograph of Raeticodactylus used in Fig. ; and S. Hartman for permission to use silhouettes from phylopic.org. This study was supported by the Royal Commission for the Exhibition of 1851–Science Fellowship awarded to D.F. R.J.B., E.M.D., A.F., D.J.L. and P.J.V. were supported by a Leverhulme Research Project Grant (RPG-2019-365).

Publisher Copyright:
© 2022, The Author(s), under exclusive licence to Springer Nature Limited.

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