Triturus, Rafinesque, 1815

Rage, Jean-Claude & Bailon, Salvador, 2005, Amphibians and squamate reptiles from the late early Miocene (MN 4) of Béon 1 (Montréal-du-Gers, southwestern France), Geodiversitas 27 (3), pp. 413-441 : 417

Triturus cf. T. marmoratus (Latreille, 1800) ( Fig. 1C )

MATERIAL EXAMINED. — 10 trunk vertebrae (Béon 2004 LT 5, 6).

COMMENTS

The vertebrae are clearly larger than those referred to as Triturus aff. T. helveticus (centrum length: from 2.52 to 3.21 mm; average: 2.84 ± 0.27 mm) and the t-test comparing the length of the centrum of this form to that of the preceding taxon is significant at the 5% level. The neural arch is moderately vaulted; the ratio neural arch height/vertebra height is 0.37 ± 0.025 and the t-test comparing this ratio to that of the vertebrae of T. aff. T. helveticus is highly significant at the 1% level. The neural spine is long, low and thin. The ventral crests appear to be weakly developed. The subcentral foramina are smaller and more numerous than in T. aff. T. helveticus .

The low neural spine demonstrates that this form belongs to the subgenus Triturus (i.e. Neotriton Bolkay, 1928 ). Although low, the neural spine is higher than that of species of the T. cristatus group, which shows that the form from Béon 1 should be assigned to the T. marmoratus-T. vittatus assemblage. In addition, the posterior part of the dorsal border of the neural spine is not flattened and lacks pits; therefore, these vertebrae do not belong to T. vittatus (Jenyns, 1835) . However, the vertebrae from Béon 1 are smaller than those of the living T. marmoratus and it should be noted that T. pygmaeus (Wolterstorff, 1905) , that was long regarded a subspecies of T. marmoratus , is now regarded as a species ( García París et al. 2001). Unfortunately, the vertebrae of T. pygmaeus are poorly known. Therefore, the specimens from Béon 1 are provisionally referred to as Triturus cf. T. marmoratus .

Estes (1981) identified the earliest member of the T. marmoratus group (as Triturus cf. T. marmoratus ) in the latest Oligocene (MP 30; early Miocene according to Estes) of Coderet, France.

Figures

FIG. 1. — Caudata; A, cf. Chelotriton sp., trunk vertebra (Béon 2004 LT 1); B, Triturus aff. T. helveticus (Razoumowsky, 1789), trunk vertebra (Béon 2004 LT 2); C, Triturus cf. T. marmoratus (Latreille, 1800), trunk vertebra (Béon 2004 LT 5). Dorsal (d), left lateral (l), right lateral (r), and ventral (v) views. Scale bars: 2 mm.