Hyloidichnus trackways with digit and tail drag traces from the Permian of Gonfaron (Var, France): New insights on the locomotion of captorhinomorph eureptiles

Abstract

Newly discovered tetrapod footprints from the middle Permian Pelitic Forma tion of Gonfaron (Le Luc Basin, Var, France) are describe d in detail and assigned to the ichn ogenu s Hyloidichnus. These specime ns are very well-preserved, with detailed trackways showing anatomical features, digit drag traces and continuous tail impressions. Together with other Hyloidichnus specime ns from the same locality and from the University of Burgund y collections, they allow the identification of the possible trackma kers of Hyloidichnus: sm all Hyloidichnus footprints are correlated with captorhinomorphs with autopodia similar to Captorhinus wh ereas large Hyloidichnus footprints might be correlated with larger captorhinomorphs or other 'basal' (eventually stem -) moradisaurines. A detailed comparative analysis is proposed to be tter un derstand the locomotion style of the trackma kers. Starting from the reconstruction of the stance ph ase of Captorhinus, we docume nt the swing ph ase of the fore-and hind -limb s of captorhinomorphs thanks to the continuous digit drag traces associated with Hyloidichnus. A link be tween gait and track preservation have be en highlighted through the analysis of tail impressions and high-resolution 3D models. In all, this stud y increases our un derstanding of captorhinomorph locomotion and enhanc es the integration of both tracks and skeletal rema ins to highlight the biome ch anics of Permian tetrapods.

Locomotor and postural diversity among reptiles viewed through the prism of femoral microanatomy: Palaeobiological implications for some Permian and Mesozoic taxa

“…The captorhinid Labidosaurus is inferred as quadrupedal with our first model, which was expected given that Labidosaurus , and Captorhinidae in general, are usually presented as quadrupedal sprawlers on the basis of osteological, muscular and ichnological evidence (Heaton & Reisz, 1980 ; Holmes, 2003 ; Logghe et al, 2021 ; Sumida, 1989 ). However, it is inferred as erect with our second model, which is more surprising, and probably wrong.…”

“…When we remove the eccentricity of the section (Ecc) from the model parameters, it comes out 'semi‐erect', which might be considered plausible. Indeed, similarities may exist between Captorhinidae and Crocodylia, at least from an ichnological perspective, with digit and tail drag tracks suggesting a similar step cycle (Logghe et al, 2021 ), although the mechanics of the limb are most likely different.…”

A new medium‐sized moradisaurine captorhinid eureptile from the Permian of Mallorca (Balearic Islands, western Mediterranean) and correlation with the co‐occurring ichnogenus Hyloidichnus

“…Peabody 1956; Logghe et al . 2021). This is supported by the correlation of the skeletal reconstruction of Tramuntanasaurus tiai to the trackway herein reported and the tracks of Hyloidichnus bifurcatus analysed by Matamales‐Andreu et al .…”

“…(2017) and Logghe et al . (2021), the last of which is focused on the correlation of Hyloidichnus to captorhinomorph trackmakers. Of relevance, this is a similar case to that reported by Voigt et al .…”

“…This has been recently demonstrated on an anatomy‐based correlation with a detailed reconstruction of the step cycles based on well‐preserved trackways (Logghe et al . 2021; see also Holmes 2003). Hyloidichnus tracks, especially those of larger size (>5 cm long), have been referred to moradisaurines (Voigt et al .…”