Albanerpetontidae, Fox & Naylor, 1982

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 : 695

Albanerpetontidae indet.

( Fig. 9 )

DESCRIPTION

Albanerpetontids are represented in Angeac-Charente by numerous and diverse bones, including dentaries, premaxillae, maxillae, vertebrae and forelimb bones ( Fig. 9 A-K). All the material was recovered from screen washing residues. It is always disarticulated, and almost always fragmentary. Several diagnostic characters allow their assignment to the Albanerpetontidae , including: 1) intertonguing symphyseal joint between dentaries, in a mortise-and-tenon style ( Fox & Naylor 1982; Milner 1988; McGowan & Evans 1995; McGowan 1996, 2002; Gardner 1999b, 2000; Gardner et al. 2003; Sweetman & Gardner 2013; Matsumoto & Evans 2018). In the Angeac-Charente specimens, there are two symphyseal prongs ( Fig. 9A, B ); 2) pleurodont, chisel-like and regularly arranged non-pedicellate teeth, labiolingually compressed and bearing three faint, mesiodistally aligned cuspules ( Fig. 9 A-G; Fox & Naylor 1982; Gardner 1999a, b, 2000; McGowan & Evans 1995; Sweetman & Gardner 2013; Matsumoto & Evans 2018); and 3) foramina arranged in line on external face of dentary ( Fig. 9F ; Fox & Naylor 1982; Gardner 2000).

In Angeac-Charente albanerpetontids, the maxilla is unornamented labially, except for scattered external nutritive foramina that are characteristic of the group ( Fig.9D ; Fox & Naylor 1982; Gardner 2000). In this respect, they differ from Albanerpeton inexpectatum from the Miocene of France ( Gardner 1999a). As in other albanerpetontid for which trunk vertebrae have been described ( Estes & Hoffstetter 1976; McGowan 1996, 2002; McGowan & Ensom 1997; Sweetman & Gardner 2013; Matsumoto & Evans 2018), those from the Angeac-Charente material ( Fig. 9 I-K) are amphicoelous, hourglass-shaped and bear a short unicipital transverse process. The centrum is narrowly constricted at its center ( Fig. 9I, K ) and the cotyles are circular in outline and have thickened rims ( Fig. 9J ). As in other albanerpetontid trunk vertebrae described elsewhere, the notochordal canal is anteroposteriorly continuous ( Fig. 9J ; Sweetman & Gardner 2013) and thus the vertebrae are fully notochordal.

Angeac-Charente specimens also show numerous features that have been described in other albanerpetontids and allow the distinction from other lissamphibians and lizards.The premaxilla ( Fig.9D, E ) and maxilla ( Fig.9C ) have a deep pars dentalis and the dentary ( Fig. 9A, B, F, G ) has a tall dental parapet, allowing the attachment of highly pleurodont teeth ( Gardner 2000). Upper jaws are also characterized by a prominent, shelf-like pars palatinum lingually ( Fig. 9E ; Gardner 2000). The maxilla has a low, posteriorly tapered pars facialis ( Fig. 9C ; Gardner 1999a, 2000). On the dentary, the Meckelian canal is closed anteriorly, and the subdental shelf is low, narrow and gutterlike anteriorly ( Fig. 9A ; Gardner 1999a, b, 2000). As in other known albanerpetontid species, the humeral condyle is spherical, fully ossified and larger than the adjacent radial epicondyle ( Fig. 9H ; Sweetman & Gardner 2013). Above this humeral ball is a triangular and well-defined cubital fossa, at the proximal extremity of which a small foramen can be seen ( Fig. 9H ), as also reported for Albanerpeton inexpectatum ( Estes & Hoffstetter 1976) and Wesserpeton evansae ( Sweetman & Gardner 2013) .

The albanerpetontids from Angeac-Charente differ from Anoualerpeton and Albanerpeton nexuosum , but resemble other Albanerpeton species, Celtedens and Wesserpeton in having dentaries and maxillae with relatively straight occlusal margins, and teeth weakly heterodont in size ( Sweetman & Gardner 2013). Unfortunately, the diagnostic characters necessary for identification at the generic level are lacking. Neither the maxilla nor the dentary is diagnostic for Albanerpeton and Celtedens ( Gardner 2000) , as their diagnoses are based on frontal characters ( Gardner 1999a, b, 2000; McGowan & Evans 1995; McGowan 2002). We did not find any frontal bones in the Angeac-Charente material, and so we cannot attribute the albanerpetontid material to these genera with certainty. Within Albanerpeton , the premaxilla is the most taxonomically informative bone for species ( Gardner 1999b, 2000), but the specimens found to date at Angeac-Charente are too incomplete to be relevant.

Thus, considering the characters mentioned above, we can attribute the Angeac-Charente specimens to the family Albanerpetontidae , but so far the material is too incomplete to allow a further attribution at the generic and specific level.

Figures

FIG. 9. — Albanerpetontid remains from Angeac-Charente: A, B, left dentary of Albanerpetontidae indet. (ANG M-101) in lingual (A) and dorsal (B) views; C, premaxillary of Albanerpetontidae indet. (ANG M-102) in ventrolingual view; D, E, left maxillary of Albanerpetontidae indet. (ANG M-51) in labial (D) and lingual (E) views; F, G, dentary fragment of Albanerpetontidae indet. (ANG M-35) in labial view showing foramina discussed in the text (F) and lingual (G) view; H, distal end of a left humerus of Albanerpetontidae indet. (ANG M-36) in ventral view; I-K, dorsal vertebra of Albanerpetontidae indet. (ANG M-103) in dorsal (I), anterior (J) and lateral (K) views. Scale bars: A-E, H-K, 400 µm; F, G, 1 mm.