Anguinae Gray, 1825

Anguinae Gray, 1825 View in CoL

Anguinae indet.

Figure 18 View Fig

Material. Seven trunk vertebrae ( UM-BFI 3077, UM-BFI 3088, UM-BFI 3132, UM-BFI 3136, UM-BFI 3192, UM-BFI 3194, and UM-BFI 3196); and one caudal vertebra ( UM-BFI 3172).

Description. UM-BFI 3077 is a trunk vertebra, missing the right prezygapophysis and the anterior portion of the neural arch ( Fig. 18a–e View Fig ). Te centrum is procoelous, with a dorsoventrally compressed cotyle and condyle (i.e., wider than high; Fig. 18a, b View Fig ). Its ventral surface is flat, with no haemal keel visible ( Fig. 18d View Fig ). Te centrum is elongated anteroposteriorly ( Fig. 18c View Fig ). Te neural canal is arched and taller than the cotyle ( Fig. 18a View Fig ). Te neural arch has a marked interzygapophyseal constriction

( Fig. 18c View Fig ). Te prezygapophysis bears an ovoid articular facet extended anteriorly ( Fig. 18c View Fig ). Te facet is oriented dorsomedially ( Fig. 18a View Fig ). Te subcentral ridges of the centrum are concave ( Fig. 18d View Fig ). A thin dorsal ridge extends on the neural arch on its entire length ( Fig. 18c View Fig ). Posteriorly, it thickens into a short neural spine ( Fig. 18c, e View Fig ). UM-BFI 3132 is identical to UM-BFI 3077 but is poorly preserved ( Fig. 18f–j View Fig ). UM-BFI 3192 and UM-BFI 3196 are also similar to UM-BFI 3077.

UM-BFI 3088 ( Fig. 18k–o View Fig ) and UM-BFI 3136 ( Fig. 18p– t View Fig ) are similar to UM-BFI 3077 and UM-BFI 3132, with the exception of the following characters: (1) articular facet of the prezygapophyses less extended anteriorly; (2) shorter and wider centrum; and (3) shorter neural spine (likely linked to a poorer preservation). UM-BFI 3194 is also similar to UM-BFI 3088 and UM-BFI 3136.

UM-BFI 3172 ( Fig. 18u–w View Fig ) is a caudal vertebra missing most of its neural arch. Te vertebra is similar to the trunk vertebrae on the following characters: (1) cotyle and condyle wider than high; (2) relatively smooth ventral surface of the centrum; and (3) neural arch not vaulted. Te para- and diapophyses are fused into a large pleurapophysis, extending laterally ( Fig. 18u–w View Fig ) .

Attribution and remarks. All these specimens are referred to Anguinae based on the following characters: (1) cotyle and condyle depressed; (2) flattened ventral surface of the centrum; and (3) neural arch not very vaulted posteriorly ( Augé, 2005; Meszoely, 1970; Rage & Augé, 2015). Note that the two former characters are also present in the North American related group Anniellinae ( Bell et al., 1995; Meszoely, 1970; Smith, 2011a). In any case, a taxonomic identification below the family level in pre-Miocene anguines is difficult when based on non-cranial elements, as several genera were present during the Paleogene of Europe and for certain of these vertebrae are so far unknown ( Augé, 2005; Čerňanský et al., 2016a; Georgalis et al., 2021a, 2021b; Klembara & Green, 2010; Vasilyan et al., 2022) and variation within the vertebral column can be high ( Georgalis & Scheyer, 2021). It should be noted that UM-BFI 3077, UM-BFI 3132, UM-BFI 3192, and UM-BFI 3196 represent an Ophisaurus -like morphotype vertebra, with: (1) subcentral ridges concave; and (2) height of the neural canal taller than the cotyle (see Čerňanský et al., 2019). As UM-BFI 3088, UM-BFI 3136, and UM-BFI 3194 differ from UM-BFI 3077 on these features, they could potentially represent a second anguine taxon from La Bouffie, but it is impossible to assess this based on such limited amount of isolated vertebrae, while admittedly, we cannot exclude that these differences can be merely attributed to some (unknown degree of) intracolumnar variation. Te genus Ophisaurus Daudin, 1803 , has been mentioned (on non-illustrated materials) from La Bouffie ( Crochet et al., 1981; later mentioned only as Anguinae indet. in Augé, 2005). Tese being said, we consider these genus-level identifications of Crochet et al. (1981) to be unfounded, pending the discovery of cranial elements from La Bouffie.