INVESTIGADORES
FIORELLI lucas Ernesto
congresos y reuniones científicas
Título:
Revision of the basal mesoeucrocodylian Microsuchus schilleri from the Bajo de la Carpa Formation (Upper Cretaceous, Neuquén, Argentina)
Autor/es:
JUÁN M. LEARDI; LUCAS E. FIORELLI; ZULMA GASPARINI
Lugar:
Mendoza
Reunión:
Congreso; 4th INTERNATIONAL PALAEONTOLOGICAL CONGRESS; 2014
Institución organizadora:
International Palaeontological Association
Resumen:
During Late Cretaceous
times, Patagonia and the rest of Gondwana was inhabited
by an astonishing fauna of crocodyliforms. After
numerous studies a more complete idea of their phylogenetic relationships and
evolutionary patterns was obtained, achieving important conclusions on
biodiversity, distribution, paleobiology and paleoecology. However, the Argentinean
taxon Microsuchus schilleri has been
almost ignored. The type specimen of Microsuchus
was recovered in the early 20?s from the Cretaceous outcrops of the Bajo de La Carpa Formation, in the area
where the campus of the University
of Comahue is actually located.
This specimen is represented by an articulated individual which has hindlimb
and axial remains although, the preservation of the materials is far from
optimal. Besides the lack of details in its remains, Microsuchus has several traits that allow us to recognize it as a
valid taxon, such as: the presence of lateral bulge
lateral to the prezygapophyses of the second sacral vertebra;
elongated posterior zeugopodia; proximal caudal centra
with triangular cross section; rectangular dorsal osteoderms; among others. On
the original description Microsuchus was
assigned as a goniopholid based on the platycely of its vertebral centra, a
character that is widely distributed among fossil crocodyliforms. A
phylogenetical analysis using an expanded data matrix focusing on postcranial
data was performed in which Microsuchus
and another long-legged crocodyliform from the same locality, Neuquensuchus, were included. The
position of Microsuchus is
conflictive as it is depicted in a politomy as a basal mesoeucrocodylian, with
its position as a neosuchian or notosuchian supported by a single synapomorphy
on the different most parsimonious trees. Additionaly, Neuquensuchus is recovered well nested among notosuchians, unlike
previous hypothesis. These findings further increase the crocodyliform
diversity of the Candeleros Formation and emphasize the relevance of its fauna in
studies of the diversification of mesoeucrocodylians and notosuchians.
Furthermore, the occurrence of both Microsuchus and Neuquensuchus
give evidence of a basal stack of basal mesoeucrocodylians with elongated limbs
that was not previosly reported for northern Patagonia.