Discoglossus sp.

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 : 364

Discoglossus sp. ( Fig. 3A )

MATERIAL EXAMINED. — Humerus: 3; ilium: 6; femur: 1; atlas: 1; trunk vertebra: 15; urostlye: 1; rib: 2.

DESCRIPTION

The best preserved humerus shows an eminentia capitata slightly lateral to the straight shaft; the crista radialis is weakly bent in ventral direction; the fossa cubitalis is deep and wide; the olecranon scar is distinctly elongate.

None of the two right and four left ilia is completely preserved but all show an elongated tuber superior, a supracetabular fossa, and a laminar crista dorsalis curved medially; the preacetabular zone is underdeveloped so that its edge nearly coincides with the anterior acetabular rim; only in one case the acetabular region is so well preserved to show a deep interiliac groove on the medial surface.

The femur has a weak femoral crest and a wellmarked sigmoid general shape.

A fragmentary atlas devoid of the neural arch shows anterior cotyles well separated by a narrow intercotylar area, a posterior cotyle elliptic in shape, and a ventral sagittal keel.

The trunk vertebrae are represented by fragments only. The vertebral centra are characteristically isolated by breakages at the level of the beginning of the neural arch (therefore it is impossible to state on a morphological basis if they were procoelous or opistocoelous); the centra are ventrally concave; cotyles are usually long and characteristically well separated from the centrum; rib bearing processes are apically flared and end with a truncated surface typical of vertebrae bearing ribs.

Two isolated ribs show a dorsal spine and an articular surface complementary to that of the rib bearing process of the vertebrae.

The proximal region of a urostyle is preserved: it shows elliptic cotyles and a couple of transverse processes.

DISCUSSION

All the described characters, the deep interiliac groove of the ilium and the ventral sagittal keel of the atlas in particular, fit well with the morphology of Discoglossus ( Böhme 1977; Bailon 1999). A key for the identification of the extant species belonging to this genus is still not available. Clarke & Lanza (1990) discussed the distinction of the two Sardinian species Discoglossus sardus Tschudi in Otth, 1837 and D. montalentii Lanza, Nascetti, Capula & Bullini, 1984 , but the osteological characters identified by them do not concern the skeletal elements preserved in the Capo Mannu D1 LF sample. The fossil remains are therefore referred to Discoglossus sp.

Figures

FIG. 3. — Fossil remains of amphibians from Capo Mannu D1 Local Fauna (Sardinia): A, Discoglossus sp., rigth ilium (DSTC 6005), lateral view; B, cf. Bufo gr. B. viridis, left ilium (DSTC 6006), lateral view; C-G, Hyla gr. H. arborea; C, rigth ilium (DSTC 6007), lateral view; D, rigth ilium (DSTC 6008), lateral view; E, left humerus (DSTC 6009), ventral view; F, left scapula (DSTC 6010), lateral view; G, presacral vertebra (DSTC 6011), dorsal view. Scale bar: 2 mm.