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.