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Yacarerani (Notosuchia) postcranial anatomy
A new online paper:
Juan Martin Leardi, Diego Pol, Fernando E. Novas & Mario Suárez Riglos (2015)
The postcranial anatomy of Yacarerani boliviensis and the phylogenetic
significance of the notosuchian postcranial skeleton.
Journal of Vertebrate Paleontology (advance online publication)
In this contribution, we describe new specimens of Yacarerani
boliviensis from the Cajones Formation (Upper Cretaceous) of Bolivia.
We focus on the postcranial anatomy of Y. boliviensis, because this
anatomical region is completely unknown in other sphagesaurid
notosuchians up to the present. At least eight individuals
representing almost the entire postcranial skeleton are described.
Although the postcranial anatomy of Yacarerani resembles that of other
notosuchians in many features, five autapomorphic characters were
identified: pedicles of the atlas bearing a lateral bulge; absence of
rounded depressions on the dorsal surface of the anterior to middle
dorsal vertebrae; coracoid bearing an oblique crest on its lateral
surface; lateromedially compressed anterior ungual phalanges; and
femur with a shallow depression for the M. puboischiofemoralis
internus 1 and M. caudifemoralis longus. Observed variation in the
postcranial anatomy of basal mesoeucrocodylians was incorporated as
new characters in a phylogenetic analysis, expanding the postcranial
information used in current phylogenetic data sets. The phylogenetic
analysis depicts Yacarerani forming a clade with Adamantinasuchus,
which is positioned at the base of Sphagesauridae. This family is well
nested among a clade of ’advanced notosuchians,’ and Mariliasuchus is
recovered as its sister group. The cladistic analysis recovered new
postcranial synapomorphies for Notosuchia and less inclusive clades,
although the fact that many taxa lack postcranial remains limits the
number of unambiguous postcranial synapomorphies within Notosuchia.