Palaeobatrachus cf. hiri, Venczel, 2004

Venczel, Márton & Stiuc, Emanoil, 2008, Late middle Miocene amphibians and squamate reptiles from Taut ,, Romania, Geodiversitas 30 (4), pp. 731-763 : 744-745

Palaeobatrachus cf. hiri ( Fig. 8 )

MATERIAL EXAMINED. — One nasal ( ISER Tt-0380), one premaxilla ( ISER Tt-0381), one pterygoid ( ISER Tt-0384), one urostyle ( ISER Tt-0385), one clavicle ( ISER Tt-0382), one tibiofibula ( ISER Tt-0386).

DESCRIPTION

Nasal

The bone is flattened and sickle-shaped with deeply concave anterior margin ( Fig. 8B ). The anterior process is tapering, while the lateral process is somewhat enlarged. The dorsal surface is smooth, whereas on the ventral surface of the lateral process a low crest is observed delimiting posteriorly

an oval depression. Premaxilla

ISER Tt-0381 represents a left premaxilla of a small individual. In dorsal view, the bone has a roughly rhomboid shape. The premaxillary alary process is thin and has a vertical orientation with its distal section damaged ( Fig. 8A ). Fine longitudinal striations on the premaxillary anterolateral side suggest that in living animal it was overlapped by the maxilla. The palatine process is relatively wide and horizontal. The number of tooth positions is four; the two preserved teeth are conical and slightly curved posteriorly. At the base of each tooth position there is a deep hole delimited laterally by two osseous knobs.

Pterygoid

The specimen is rather fragmentary with the tips of all three pterygoidal rami damaged ( Fig. 8C ). The anterior ramus was presumably rather long and exhibits at its dorsomedial surface a moderately deep sulcus pterygoideus; the medial tubercle is weakly developed. Near the base of the medial and posterior ramus the bone is considerably widened.

Urostyle

In ISER Tt-0385, the neural lamina and the posterior portion of the shaft are broken off ( Fig. 8D ). The specimen displays a bicotylar condition with the ventral cotylar margins projecting anteriorly; vestige of a putatively small intercotylar process is also present.

Clavicle

ISER Tt-0382, belonging to a rather small individual, is the only specimen referable to this taxon. The bone is strongly curved and somewhat depressed dorsoventrally. A rather small processus scapularis is situated above the facies glenoidalis claviculae, the latter contributing to the formation of cavitas glenoidalis for the humeral head ( Špinar 1972). The medial extremity is also missing but it exhibits posteriorly a rather shallow sulcus pro cartilagine precoracoidalis.

Tibiofibula

ISERTt-0386 is a fragmentary tibiofibula, preserving

the proximal part of the diaphysis with the epiphysis

Late middle Miocene amphibians and reptiles from Taut,, Romania

completely ossified; it belonged to a rather old individual ( Fig. 8E ). The condylus medialis and the condylus lateralis are well differentiated (the former projects more dorsally), while the crista ossis cruris is rather prominent near the proximal extremity of the condylus medialis.

REMARKS

The available remains closely resemble those of P.hiri Venczel, 2004 , known from the middle Miocene (MN 6) of Sámsonháza and from the late middle Miocene (MN 7) of Mátraszőlős, N Hungary. The assignment mainly rests on the morphology of nasal, the shape of which is reminiscent not only of P. hiri , but to some extent of P. laubei Bieber, 1881 . The latter is known from the lower Oligocene (MP 21) of Suletice, Czech Republic ( Špinar 1972), and contrary to P. hiri its frontoparietal (unknown at Tauţ) is devoid of parasagittal ridges.The specimens from both Mátraszőlős and Tauţ localities exhibit a similarly shaped notch on the ventral surface of the lateral ramus of the nasal (this feature is unknown in P. laubei ). Actually, the latter structure could represent the articulation surface with the maxillary nasal process, which is rounded labially (see Venczel 2004: text-fig. 3H). However, the number of premaxillary tooth positions in the Tauţ specimen is lower (4) than in those of P. hiri (6-10), which might result from ontogenetic variation.

Family PELOBATIDAE Bonaparte, 1850

Figures

FIG. 8. — Palaeobatrachus cf. hiri: A, premaxilla (ISER Tt-0381), posterior view;B, nasal (ISER Tt-0380),ventral view;C, pterygoid (ISER Tt-0384), dorsal view; D, urostyle (ISER Tt-0385), dorsal view; E, tibiofibula (ISER Tt-0386), posteromedial view. Scale bar: 2 mm.