INVESTIGADORES
SCANFERLA Carlos Agustin
congresos y reuniones científicas
Título:
New evidences about the early evolution of derived macrostomatans (Squamata, Serpentes)
Autor/es:
CARLOS AGUSTÍN SCANFERLA; FERNANDO EMILIO NOVAS; CHRISTIAN DE MUIZON; RICARDO CÉSPEDES
Lugar:
Trelew
Reunión:
Jornada; Jornadas Argentinas de Paleontología de Vertebrados; 2007
Resumen:
Tropidophiids are currently represented by two extant forms (Tropidophis and Trachyboa), restricted to the Neotropical biogeographical realm. Except for some vertebral remains, no other evidence was available about extinct tropidophiids in tropical America. Here we report a new and indisputable member of this family, from the Tiupampa fossil site, a highly productive early Late Paleocene locality in central Bolivia. This new snake (Museo de Historia Natural de Cochabamba MHNC 1321) constitutes the best known South American Paleocene snake ever discovered, being represented by articulated cranial and postcranial material. Macrostomatan ("advanced snakes") traits present in the new snake are: rostral portion of prefrontal bone covering the nasal gland as well as roofing the aditus conchae, and lateroventral portion of prefrontal (serving for articulation with the maxilla) caudally positioned. Moreover, tropidophiid features include palatine with wide and plate-like vomerine process, lacrimal foramen piercing the maxilla/prefrontal contact, and proximal postorbital extremely bifurcated. The new snake exhibits a well developed coronoid bone, in sharp contrast with living tropidophiids, in which this bone is absent or fused to the compound bone. A remarkable postcranial trait of MHNC 1321 is the presence of an haemal keel in mid-posterior trunk vertebrae, in contrast with the "plate-like" morphology that characterize extant tropidophiids. The new discovery reinforces the South American origin of Tropidophiidae, but most importantly it indicates that the diversification of derived macrostomatans was well underway during the early Late Paleocene, at least.