The postcranial skeleton of the gliding reptile Coelurosauravus elivensis Piveteau, 1926 (Diapsida, Weigeltisauridae) from the late Permian of Madagascar

ABSTRACT

The postcranial skeleton of the gliding neodiapsid reptile Coelurosauravus elivensis (Lower Sakamena Formation, ?upper Permian, southwestern Madagascar) is re-described in detail based on all previously referred specimens. The exquisite preservation of the material provides three-dimensional details of the individual bones, which are missing in the Laurasian weigeltisaurid material. A new skeletal reconstruction of C. elivensis is proposed including the first reconstruction of a weigeltisaurid reptile in lateral view. The re-examination of the material highlights interspecific differences in the postcranium of weigeltisaurids, in particular in the trunk and patagial spars. These animals have long been considered as arboreal and gliding reptiles. However, new information on the postcranium of C. elivensis reveals strong similarities with both extant and extinct quadrupeds specialized for a clinging arboreal lifestyle. Additionally, the presence of an additional phalanx in the fifth digit of the manus is now attested for all weigeltisaurids where this region is preserved. We suggest that this morphology could have allowed weigeltisaurids to grasp their patagium as observed in the extant gliding agamid Draco. Weigeltisaurids are thus the earliest known gliding vertebrates and some of the first tetrapods with an obligatory arboreal lifestyle, but also represent the only known vertebrates with a hyperphalangy aligned with a gliding apparatus.

ACKNOWLEDGMENTS

We thank N.-E. Jalil (MNNH) for access to the MNHN specimens and constructive discussions on weigeltisaurids and Permo–Triassic amniotes. Many thanks to C. Letenneur (MNHN) for her life reconstruction of Coelurosauravus. Thanks also to D. M. Henderson (TMP) for his help in the examination of Wapitisaurus. We thank O. Béthoux (MNHN) for his help in RTI methodology and loaning the necessary hardware to V.B., and P. Loubry (CNRS) and D. Germain (MNHN) for their help in photography. We also thank J. Falconnet (MNHN), A. Pritchard (VMNH) and H.-D. Sues (NMNH) for constructive discussions on weigeltisaurids and Permo–Triassic reptiles. Finally, we thank X. Jenkins and an anonymous reviewer for their constructive reviews of the manuscript, and G. Bever and L. Leuzinger for their editorial work. This work is supported by the French Ministry of Superior Education and Research (annual credits of the CR2P and Ph.D. grant to V.B.).

DATA AVAILABILITY

The data underlying this article are available in Zenodo, at http://doi.org/10.5281/zenodo.6078599.