Amphisbaenia, Gray, 1844

Delfino, Massimo, Bailon, Salvador & Pitruzzella, Gaetano, 2011, The Late Pliocene amphibians and reptiles from “ Capo Mannu D 1 Local Fauna ” (Mandriola, Sardinia, Italy), Geodiversitas 33 (2), pp. 357-382 : 373

Amphisbaenia indet. ( Fig. 6 A-C)

MATERIAL EXAMINED. — Trunk vertebra: 16; caudal vertebra: 1.

DESCRIPTION

The trunk vertebrae have a maximum centrum length of 1.5 mm. They show a rather uniform morphology with distinctly dorsoventrally depressed cotyles and condyles; wide oval-shaped prezygapophyses characteristically “protruding” from the rest of the vertebra in dorsal view and bearing large and short blunt processes; well-defined globular synapophyses; convex anterior and concave posterior edge of the neural arch; underdeveloped neural crest (in some cases a hint of a ridge terminating in a flattened area can be present close to the posterior end of the neural arch); depressed neural arch (when seen in posterior view); flattened ventral surface of the centrum with parallel lateral margins and two small foramina in the anterior region.

The caudal vertebra has a similar morphology but differs for the absence of prezygapophyseal processes and for the presence of anterior transverse and posterior haemal processes fused to the centrum.

DISCUSSION

The combination of the morphological characters described above allows to identify a member of the

Amphisbaenia , but due to the fact that isolated amphisbaenian vertebrae are generally not diagnostic even at genus level, a precise taxonomic allocation is not possible (see Delfino 1997, and literature therein). It is however likely that these vertebrae belong to Blanidae Kearney, 2003 , the only family that has been identified so far in the European fossil record. The fossil remains are morphologically congruent with the extant genus Blanus Wagler, 1830 and not with, for example, Trogonophis wiegmanni Kaup, 1830 ( Morocco) whose vertebrae are comparatively more elongated and narrow.

Noteworthy is that Venczel &Sanchiz (2006) listed the presence of Blanus gracilis (Roček, 1984) in the Lower Miocene Sardinian site of Oschiri. This species was originally described on the basis of isolated vertebrae which are notoriously poorly informative ( Rage 1988; Delfino 1997; Augé 2005) but it seems that tooth bearing bones are present at Oschiri and that therefore a valid diagnosis of this taxon based on diagnostic characters could be possible. In any case, the absence of tooth bearing elements in the Capo Mannu D1 LF does not allow confirmation of the possible survival of this taxon in Sardinia.

Order SERPENTES Linnaeus, 1758

Figures

FIG. 6. — Fossil remains of reptiles from Capo Mannu D1 Local Fauna (Sardinia): A-C, Amphisbaenia indet., trunk vertebra (DSTC 6021), dorsal, left lateral and ventral views; D-F, Eryx cf. E. jaculus, trunk vertebra (DST 6022), dorsal, ventral and posterior views; G, caudal vertebra (DSTC 6023), anterior view. Scale bars: 2 mm.