Cteniogenys, Gilmore, 1928

Allain, Ronan, Vullo, Romain, Rozada, Lee, Anquetin, Jérémy, Bourgeais, Renaud, Goedert, Jean, Lasseron, Maxime, Martin, Jeremy E., Pérez-García, Adán, Fabrègues, Claire Peyre De, Royo-Torres, Rafael, Augier, Dominique & Bailly, Gilles, 2022, Vertebrate paleobiodiversity of the Early Cretaceous (Berriasian) Angeac-Charente Lagerstätte (southwestern France): implications for continental faunal turnover at the J / K boundary, Geodiversitas 44 (25), pp. 683-752 : 703

cf. Cteniogenys

( Fig. 16 A-E)

DESCRIPTION

A characteristic robust vertebra ( Fig. 16 A-C), as well as a smaller vertebra that probably belongs to a juvenile individual ( Fig. 16D, E ), have been discovered among the microremains. Both centra are amphicoelous, with an opened neurocentral suture. Dorsally, a distinct longitudinal ridge is laterally bordered by longitudinal grooves on the floor of the neural canal ( Fig. 16A ). In ventral view, the lower half of the centrum is pinched into a keel ( Fig. 16D ). The margins of the cotyle are thick ( Fig. 16E ). All these characters are reminiscent of choristoderan reptiles ( Evans 1991; Averianov et al. 2006; Vullo et al. 2014; Haddoumi et al. 2016; Lasseron et al. 2020). ANG M-20 is nearly identical to the vertebra of Cteniogenys figured by Evans & Milner (1994: fig.18.5). Hence, it is here tentatively assigned to this genus, although this identification needs to be substantiated with additional material. These freshwater or amphibious diapsids are well known in Laurasia ( Matsumoto et al. 2013), but have also been reported from the Jurassic-Cretaceous transition of North Africa ( Lasseron et al. 2020). In the Lower Cretaceous of Asia, the diversity and abundance of choristoderans is particularly high in the faunal assemblages, in which crocodyliforms are scarce ( Matsumoto et al. 2015; Skutschas & Vitenko 2017). Conversely, the abundance and diversity of crocodyliforms at Angeac-Charente may explain the scaricity of choristoderans.

Figures

FIG. 16. — Choristoder remains from Angeac-Charente: A-C, anterior dorsal vertebra of cf. Cteniogenys sp. (ANG M-20) in dorsal (A), ventral (B) and posterior (C) views; D, E, juvenile dorsal vertebral centrum (ANG M-47) in ventral (D) and oblique anterior (E) views. Scale bar: A-C, 1 mm; D, E, 200 µm.