Re-evaluation of the type material of “Diasemosaurus occidentalis” Ameghino and “Dibolosodon typicus” Ameghino (Squamata: Teiidae) from the Miocene of Argentina

BRIZUELA, S.; ALBINO, A. M.

JOURNAL OF VERTEBRATE PALEONTOLOGY

SOC VERTEBRATE PALEONTOLOGY

Año: 2008 vol. 28 p. 253 - 257

0272-4634

In 1893, Florentino Ameghino described two new genera and species of extinct lizards of uncertain affinities, Diasemosaurus occidentalis and Dibolosodon typicus, both from the levels of the Santa Cruz Formation (early-mid Miocene) at the Monte León locality (southern Patagonia), Santa Cruz province, Argentina. In the contribution presented here the holotype material of Diasemosaurus and Dibolosodon is redescribed and assigned to the extant genus Tupinambis (Squamata: Teiidae). It includes adult and young individuals. The blunt posterior tooth of the adult specimen is identical to that of adult Tupinambis but with the size of a young, smaller form. The size inferred for the Tupinambis specimens at Monte León is intermediate between early Miocene specimens from Gaiman (northeastern Patagonia) and the most derived extant Tupinambis species. This suggests a progressive increment in size in time. The presence of this genus so far south in Patagonia constitutes the southernmost record of teiids and demonstrates that their distribution during the early-mid Miocene surpassed 50ºS in latitude, according to the warm and humid climatic conditions postulated for the Santacrucian SALMA.