Lissotriton, Bell, 1839

Venczel, Márton & Stiuc, Emanoil, 2008, Late middle Miocene amphibians and squamate reptiles from Taut ,, Romania, Geodiversitas 30 (4), pp. 731-763 : 738-739

Lissotriton sp. ( Fig. 4 )

MATERIAL EXAMINED. — One frontal ( ISER Tt-0350), one atlas ( ISER Tt-0351), eight presacral vertebrae ( ISER Tt-0352/1-8).

DESCRIPTION

Frontal

The dorsal surface bears a fine sculpture formed by

shallow ridges and pits ( Fig. 4A ). The supraorbital margin is low; parallel to the latter, a deep and widening furrow is directed anteriorly. The relatively short posterolateral process tapers distally, and its posterior edge only slightly exceeds the posterior margin of the frontal. This morphology is suggestive of an incomplete or a somewhat weak frontosquamosal arch.

Atlas

In the single specimen only the centrum is preserved. The subcentral surface is slightly concave, triangleshaped and provided with two relatively large subcentral foramina ( Fig. 4B ). The articular surface of the paired atlantal condyles is of circular shape. The odontoid process is partially divided exhibiting two shallowly convex ventrolateral articular surfaces of oval shape. The atlantal cotyle is circular.

Presacral vertebrae

All the specimens are small sized with relatively short and opisthocoelous centrum ( Fig. 4 C-C’’). The neural arch is moderately vaulted and provided with a relatively high neural spine forking posteriorly. The dorsal margin of the latter structure is not widened laterally.

REMARKS

Based on the available material, the above taxon may be securely placed in the genus Lissotriton . Among members of Lissotriton the postfrontal process is rather long in L. helveticus (Razoumovsky, 1789) and L. boscai (Lataste, 1879) but is relatively short in L. montandoni (Boulenger, 1880) and L. vulgaris (Linnaeus, 1758) , the later displaying a morphology fairly similar with that of ISER Tt-0350. The size and morphology of the trunk vertebrae, with relatively high neural arch and well-developed neural spine forking posteriorly, support also the taxonomic assignment of the above fossils. Lissotriton roehrsi (Herre, 1955) , an extinct member of the genus, known from the early to late Miocene of Central Europe ( Sanchiz 1998a; Böhme & Ilg 2003), differs from the other ingroup taxa by having a relatively high neural spine provided with a distinct dorsal enlargement of the dorsal margin. Furthermore, Sanchiz (1998a) reported numerous

skeletal remains assigned to Lissotriton (= Triturus )

Late middle Miocene amphibians and reptiles from Taut,, Romania

roehrsi from the late early Miocene (MN 4) of Obersdorf, Austria. The frontals are provided with a relatively long postfrontal process and with an extensive sculptured dorsal surface differing clearly from the Tauţ specimen.

The earliest fossil record of the genus Lissotriton might be from the late early Miocene (MN 4) of Béon 1, France, described under the name Triturus aff. T. helveticus by Rage & Bailon (2005) and Obersdorf, Austria (Sanchiz 1988a), suggesting an already wide distribution of this group during late early Miocene.

Figures

FIG. 4.— Lissotriton sp.:A, frontal (ISER Tt-0350);B, atlas (ISER Tt- 0351);C-C’’, presacral vertebra (ISER Tt-0352/1);A, C, dorsal views; B, C’, ventral views; C’’, right lateral view. Scale bar: 2 mm.