Redescription and reevaluation of the taxonomical status of Microsuchus schilleri
Publicado por Leonardo Filippi en 14:37
Juan
Martín Leardi, Lucas E. Fiorelli, and Zulma Gasparini
Fragmentary remains of Microsuchus schilleri (Crocodyliformes:
Mesoeucrocodylia) from the Bajo de La Carpa Formation (Santonian, Late
Creteceous) of northern Patagonia, Argentina, are decribed and reevaluated
taxonomically. The type specimen is an articulated individual with hindlimb and
axial remains. Microsuchus has several traits that allow to recognize it as a
valid taxon (the presence of bulge lateral to the prezygapophyses of the second
sacral vertebra; elongated posterior zeugopodia; proximal caudal centra with
triangular cross section). Microsuchus
was originally assigned as a goniopholidid 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-limbed crocodyliform from the same location, Neuquensuchus, were included. Microsuchus
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 well nested among
notosuchians, in contrast to previous hypothesis. These findings further
increase the crocodyliform diversity of the Bajo de la Carpa 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 gives evidence of a basal stock of mesoeucrocodylians
with elongated limbs that was not previously reported for northern Patagonia.
Leardi, J.M, Fiorelli,
L.E. and Gasparini, Z. 2015.Redescription
and reevaluation of the taxonomical status of Microsuchus schilleri (Crocodyliformes: Mesoeucrocodylia) from the Upper
Cretaceous of Neuquen, Argentina. Cretaceous
Research 52 (2015) 153e166
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