N . merkurensis N . longivertebrata N . sansaniensis ( Ivanov 2002 ) N . sansaniensis Natrix N . sansaniensis Natrix merkurensis , Ivanov (2002) N . merkurensis N . sansaniensis Amphibians and squamate reptiles from the late early Miocene (MN 4) of Béon 1 (Montréal-du-Gers, southwestern France) Rage, Jean-Claude Bailon, Salvador Geodiversitas 2005 27 3 413 441 Laurenti 1768 [725,798,812,837] Reptilia Natricidae Natrix Animalia Squamata 17 430 Chordata genus  MATERIAL EXAMINED. — 24 trunk vertebrae (Béon 2004 LT 70, 71).  COMMENTS    N. merkurensisis 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. longivertebrataand 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. sansaniensisby Szyndlar & Schleich (1993)who reported it as  Natrixaff.  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,  Natrixaff.  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 sa 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. merkurensisfrom Merkur-North; consequently, this natricine from Béon 1 is referred to as  Natrixaff.  N. merkurensis.