Unnamed spinosaur from Brazil

[Tim Williams <twilliams_alpha@hotmail.com>]

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. 
62(3): 309-320

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.