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Wintonotitan (Sauropoda: Titanosauriformes) revised (free pdf)



Ben Creisler
bcreisler@gmail.com


A new paper currently in open access:

Stephen F. Poropat, Philip D. Mannion, Paul Upchurch, Scott A.
Hocknull, Benjamin P. Kear and David A. Elliott (2014)
Reassessment of the non-titanosaurian somphospondylan Wintonotitan
wattsi (Dinosauria: Sauropoda: Titanosauriformes) from the
mid-Cretaceous Winton Formation, Queensland, Australia.
Papers in Palaeontology (advance online publication)
DOI: 10.1002/spp2.1004
http://onlinelibrary.wiley.com/doi/10.1002/spp2.1004/abstract

Free pdf:

http://onlinelibrary.wiley.com/doi/10.1002/spp2.1004/pdf


Wintonotitan wattsi, a Cretaceous titanosauriform sauropod from
central Queensland, Australia, is redescribed following a full
revision of its osteology. The holotype specimen, a partial
postcranial skeleton derived from the lower Upper Cretaceous Winton
Formation, comprises axial and appendicular elements. Wintonotitan has
been commonly resolved as a non-titanosaurian somphospondylan
titanosauriform since its description, in contrast to its more derived
contemporary Diamantinasaurus matildae. We provide a detailed
redescription, taking this opportunity to correct four
misinterpretations made in the original description of Wintonotitan
that impact on our understanding of this taxon: the right ulna was
originally described as the left and vice versa; the left metacarpus
was incorrectly described as being from the right side; metacarpal IV
was described as metacarpal V and vice versa; and the ilium was
incorrectly oriented. The reassessment of the metacarpus is
particularly important, since it shows that a proximal fossa is
present on metacarpals I, II and III, which might have been occupied
by either the strongly convex distal end of the radius or a (possibly
unossified) carpal element. We provide a review of titanosauriform
metacarpal morphology to support our reassessments. Our revision of
the osteology of Wintonotitan results in the identification of several
previously unrecognized autapomorphies, augmenting and revising its
original diagnosis. We provide additional support for the previous
referral of four caudal vertebrae from south-east of Winton,
Queensland, to W. wattsi. Furthermore, we demonstrate that a tentative
report of titanosaur osteoderms from the Winton Formation was based on
misidentification of dorsal vertebral neural spines pertaining to the
holotype of W. wattsi. Consequently, titanosaur osteoderms are
currently unknown from Australia. Following our revision and
reinterpretation of a number of elements, we re-examine the
phylogenetic placement of Wintonotitan, supporting its position as a
non-titanosaurian somphospondylan titanosauriform, with no close
relationship with the contemporaneous lithostrotian titanosaur
Diamantinasaurus.