Mongolosaurus revised

[bh480@scn.org]

From: Ben Creisler
bh480@scn.org

In case this online advance-publication paper has not 
been mentioned yet:

Philip D. Mannion (2010)
A reassessment of Mongolosaurus haplodon Gilmore, 1933, a 
titanosaurian sauropod dinosaur from the Early Cretaceous 
of Inner Mongolia, People's Republic of China.
Journal of Systematic Palaeontology (advance online 
publication)
http://www.informaworld.com/smpp/content~db=all~content=a9
31342686~frm=abslink  

The Early Cretaceous of China has yielded a diverse 
sauropod fauna, dominated by basal titanosauriforms. 
Known from a basicranium, teeth and the first three 
cervical vertebrae, Mongolosaurus haplodon is a poorly 
understood taxon whose evolutionary relationship to other 
sauropods has remained uncertain. Redescription of 
Mongolosaurus identifies key features that confirm its 
titanosaurian affinities and demonstrate its validity, 
based on several autapomorphies and a unique combination 
of characters. Diagnostic features include: a low neural 
spine which does not extend above the epipophyses; the 
dorsal edges of the posterior articular surfaces of 
anterior cervical vertebrae projecting more posteriorly 
than the ventral edges; and postaxial 
spinoprezygapophyseal laminae forming a dorsoventrally 
elongate X-shape in anterior view. Mongolosaurus is 
incorporated into three independent cladistic analyses; 
however, its precise phylogenetic position within 
Titanosauria remains unclear. This is partly a 
consequence of the limited material, but also reflects 
the unusual combination of basal and derived features for 
this clade and the need for a better understanding of 
titanosaur intra-relationships. Reassessment of this 
animal provides new information on the atlas-axis 
complex, which is extremely poorly known in titanosaurs, 
and highlights several new characters that may prove 
useful in future phylogenetic analyses, such as the ratio 
of the transverse widths of the basal tubera and 
occipital condyle. A number of features pertaining to 
both the cranial material and cervical vertebrae are 
similar to those seen in some diplodocoids (including an 
anteroventral projection on the atlantal intercentrum and 
distal bifurcation of anterior cervical neural spines), 
providing further evidence for convergence between these 
two major neosauropod radiations. Other remains 
previously attributed to Mongolosaurus from China and 
Russia cannot be referred to this genus. In summary, 
Mongolosaurus represents one of the earliest known 
titanosaurs from eastern Asia and adds to our 
understanding of this diverse clade of sauropods.