A new cranial reconstruction ofCoelurosauravus elivensisPiveteau, 1926 (Diapsida, Weigeltisauridae) and its implications on the paleoecology of the first gliding vertebrates

Abstract

The cranial skeleton of the enigmatic gliding neodiapsid reptile Coelurosauravus elivensis (Lower Sakamena Formation, Lopingian, Southwestern Madagascar) is re-described in detail. All previously referred specimens are re-examined under both direct observations and Reflectance Transformation Imaging. Their exquisite preservation yields detailed three-dimensional information on the outline of individual bones and their osteological relationships, which are missing in the Laurasian remains. In contrast to previous studies, the ontogenetic maturity of all specimens is re-affirmed. Previously unidentified elements of the palate, braincase and mandible are described, and a novel reconstruction is proposed, including the first palatal reconstruction in a weigeltisaurid reptile.C. elivensis has the smallest skull of all weigeltisaurids and differs from other species in its facial ornamentation, parietosquamosal frill and larger anterior maxillary dentition. We also provide extensive comparisons with contemporaneous reptiles, possibly closely related taxa and more recent analogs, as well as a preliminary discussion of the functional anatomy of the peculiar cranial morphology of weigeltisaurids. The cranial skeleton is a truss construction with large orbits and temporal fenestrae. By analogy with extant chamaeleonids, the elongate parietosquamosal frill is associated with an increase in length and diameter of the temporal jaw adductors, resulting in an increased gape and/or bite force and speed. Additionally, the spikes and frills of weigeltisaurids most likely served as a display and defensive structure.

The postcranial skeleton of the gliding reptileCoelurosauravus elivensisPiveteau, 1926 (Diapsida, Weigeltisauridae) from the late Permian of Madagascar

“…Gould, 1974;Benton, 2010;Padian and Horner, 2011;Hone and Faulkes, 2014). This is particularly true for weigeltisaurids in light of the scarcity of specimens and their phylogenetical distance to recent analogues (Buffa et al, 2021). As a result, the interpretations discussed here must remain speculative.…”

“…This should not be taken as a disagreement with Pritchard et al's (2021) reexamination of this specimen, but as the result of a more cautious consideration of the species W. jaekeli itself. As stated by Buffa et al (2021), this standpoint highlights the need for reexamination of this species' diagnosis in light of other Western European specimens, especially since such a revision may result in W. jaekeli being recovered as a junior synonym of Gracilisaurus ottoi (see Haubold and Shaumberg, 1985).…”

“…A more comprehensive review of the first excavations led by J.-M. Colcanap in southwestern Madagascar during the early 20 th century is underway by VB. Buffa et al (2021) provide an overview of current challenges and uncertainties in weigeltisaurid taxonomy. We follow their taxonomic framework (Table 1), summarized as Europe are referred to as Rautiania sp.…”

“…All of these characters are commonly used as indicators of morphological maturity in extinct reptiles, such as the coeval stem-saurians from the late Permian of Madagascar (Currie, 1981a;Currie and Carroll, 1984;Caldwell, 1995). The postcranium thus conforms with the evaluation of Buffa et al (2021) of the ontogenetic maturity of all Coelurosauravus specimens.…”

“…Bulanov and Sennikov (2015a) interpreted a circular element close to the braincase of MNHN.F.MAP317a as the occipital condyle, formed entirely by the basioccipital. However, as this does not conform to the better-preserved basioccipital of MNHN.F.MAP327a (Buffa et al, 2021), we identify this element as an atlantal vertebral centrum in posteroventral view based on its position relative to the braincase and neck of the animal (Figs. 8C, 8D).…”