Eurheloderma Hoffstetter, 1957

Eurheloderma Hoffstetter, 1957

cf. Eurheloderma sp.

Figure 19 View Fig

Material. One left dentary ( UM-BFI 3087).

Description. UM-BFI 3087 preserves most of the posterior region ( Fig. 19 View Fig ). Te dentition is almost identical to the maxilla assigned to Palaeovaranus (see also below). Te ventral region of the dentary is not preserved, but the sulcus Meckeli is fully opened ventrally and lingually

( Fig. 19a, b View Fig ). It narrows anteriorly by the expansion of the dental shelf ( Fig. 19a, b View Fig ). Posterior to the tooth row, the coronoid process and articulation is small. Te intramandibular septum is preserved with a short but thick posterior spine ( Fig. 19a, b View Fig ; “eminence” in Bhullar & Smith, 2008). On the labial surface, labial foramina pierce the dentary’s mid-length ( Fig. 19f, j View Fig ).

Attribution and remarks. Tree large lizards with teeth exhibiting developed plicidentine folds are present in the Eocene of the Quercy Phosphorites, i.e., Eurheloderma , Palaeovaranus , and Saniwa Leidy, 1870 . Among them, Palaeovaranus and Eurheloderma both exhibit a distinct posterior spine on the intramandibular septum ( Bhullar & Smith, 2008; Georgalis et al., 2021a). However, the posterior spine in UM-BFI 3087 is thicker than the one observed in Palaeovaranus (see Georgalis et al., 2021a: fig. 46) and in fact, resembles more the one in Eurheloderma (see figs. in Hoffstetter, 1957; see also figs. of helodermatid dentaries in Bhullar & Smith, 2008). Indeed, a similar prominent structure (“eminence”) can be observed in Miocene and extant North American helodermatids (e.g., Bhullar & Smith, 2008: figs. 1, 6) and one paratype dentary (MNHN.F.QU17596) of Eurheloderma gallicum (Krister Smith, personal communication; GLG, personal observation – note though that this structure is not clearly discernible in the published drawing of Hoffstetter [1957: fig. 3A], but it is prominent in the actual specimen). As a further note, we remark that a somehow prominent eminence of the intramandibular septum is also observed in a dentary (NHMW 2019/0058/0054) previously described and figured by Georgalis et al., (2021a: figs. 46–47) from the “old collections” of Quercy, which they attributed to Palaeovaranus ; nevertheless, the coronoid articulation of NHMW 2019/0058/0054 is much different than that of UM-BFI 3087. In the current state of knowledge, it is difficult to assess if this eminence is unique to Eurheloderma (and thus NHMW 2019/0058/0054 would be a helodermatid and not a palaeovaranid) or whether it is more variable among large Eocene anguimorphs. Tus, we tentatively assign UM-BFI 3087 to cf. Eurheloderma .