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Unnamed spinosaur from Brazil
De Souza-Bittencourt, J., and Kellner, A.W.A. (2004). On a sequence of
sacrocaudal theropod dinosaur vertebrae from the Lower Cretaceous Santana
Formation, northeastern Brazil. Arquivos do Museu Nacional Rio de Janeiro.
ABSTRACT: Besides being rare, most theropod remains from fossil deposits of
Brazil are incomplete. Up to date the Romualdo Member (Aptian/Albian) of the
Santana Formation yielded six theropod specimens. To those we add the
description of a sequence of three posterior sacral and six anterior caudal
vertebrae with three chevrons (MN 4743-V). Differences between MN 4743-V
and members of the major theropod clades such as Ceratosauria, Allosauroidea
and Coelorusauria do not allow its assignment to one of those groups.
Instead, MN 4743-V is referred to the Spinosauroidea (Spinosauridae plus
Torvosauridae), based on the presence of three robust laminae below the
transverse process of the anterior caudals, which delimit three fossae. The
lack of paired processes on the chevrons suggest that within Spinosauroidea
MN 4743-V is a member of the Spinosauridae. This is congruent with previous
findings of spinosaurids in the Romualdo Member. MN 4743-V differs from the
remaining specimens that present sacrocaudal elements indicating the
co-existence of at least five theropod species in this deposit.