Amphibians and squamate reptiles from the late early Miocene (MN 4) of Béon 1 (Montréal-du-Gers, southwestern France) Author Rage, Jean-Claude UMR CNRS 5143, Département Histoire de la Terre, Muséum national d’Histoire naturelle, case postale 38, 57 rue Cuvier, F- 75231 Paris cedex 05 (France) jcrage @ mnhn. fr jcrage@mnhn.fr Author Bailon, Salvador UMR CNRS 6569, Laboratoire départemental de Préhistoire du Lazaret, 33 bis boulevard Franck Pilatte, F- 06300 Nice (France) sbailon @ lazaret. unice. fr text Geodiversitas 2005 27 3 413 441 journal article 10.5281/zenodo.5378363 1638-9395 5378363 Natrix aff. N . merkurensis Ivanov, 2002 ( Fig. 6B ) MATERIAL EXAMINED. — 24 trunk vertebrae (Béon 2004 LT 70, 71). COMMENTS N . merkurensis is based on vertebrae and skull bones from Merkur-North (MN 3; Czech Republic ). The vertebrae are mainly characterized by the peculiar combination of an elongate and narrow centrum that is reminiscent of N . longivertebrata and a neural spine as high as that of N . sansaniensis ( Ivanov 2002 ) . The species might be present also at Petersbuch 2 (MN 4; Germany ). A natricine from the latter locality was first regarded as a possible variant of N . sansaniensis by Szyndlar & Schleich (1993) who reported it as Natrix aff. N . sansaniensis . But, after having described Natrix merkurensis , Ivanov (2002) suggested that the snake from Petersbuch 2 belongs to the latter species. However, Szyndlar & Schleich (1993) noted that the main characteristic of the natricine from Petersbuch 2 is verteb r a l p o l y m o r p h i s m a n d t h e y h i n t e d a t t h e possible presence of more than a single species. Therefore, it may be entertained whether all vertebrae from Petersbuch 2 or only a part of them belong to N . merkurensis . Both N . sansaniensis A(d) A(l) A(v) FIG. 6. — Snakes; A , Python europaeus Szyndlar & Rage, 2003 , trunk vertebra (Béon 93 E3 SN 3); B , Natrix aff. N . merkurensis Ivanov, 2002 , trunk vertebra (Béon 2004 LT 70). Anterior ( a ), dorsal ( d ), left lateral ( l ), posterior ( p ), right lateral ( r ), and ventral ( v ) views. Scale bars: 5 mm. a n d N . m e r k u r e n s i s a r e p e r h a p s p r e s e n t a t Petersbuch 2. At Béon 1, all vertebral characters, but one, are consistent with N . merkurensis : centrum elongate and narrow; subcentral ridges prominent; hypapophysis prolonged anteriorly by a prominent keel; neural spine high; dorsal edge of neural spine slightly forked anteriorly and posteriorly; tip of hypapophysis rounded; prezygapophyseal facets rather broad for typical Natrix ; subcotylar tubercles present; parapophyseal processes directed anteriorly (rarely anteroventrally); epizygapophyseal spines present. The only difference is that, at Béon 1, the prezygapophyseal processes are shorter than those of N . merkurensis from Merkur-North; consequently, this natricine from Béon 1 is referred to as Natrix aff. N . merkurensis .