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Brontomerus, new Utah sauropod



From: Ben Creisler
bh480@scn.org

I waited a bit on this one in case Mike Taylor wanted to 
announce it, but I'll go ahead now:

http://www.app.pan.pl/article/item/app20100073.html

Michael P. Taylor, Mathew J. Wedel, and Richard L. 
Cifelli (2011)
Brontomerus mcintoshi, a new sauropod dinosaur from the 
Lower Cretaceous Cedar Mountain Formation, Utah, USA.
Acta Palaeontologica Polonica in press
available online 03 Jan 2011 doi:10.4202/app.2010.0073

Brontomerus mcintoshi is a new genus and species of 
sauropod dinosaur from the Hotel Mesa Quarry in Grand 
County, Utah, U.S.A., in the upper part of the Ruby Ranch 
Member (Aptian?Albian) of the Lower Cretaceous Cedar 
Mountain Formation. It is known from at least two 
fragmentary specimens of different sizes. The type 
specimen is OMNH 66430, the left ilium of a juvenile 
individual; tentatively referred specimens include a 
crushed presacral centrum, a complete and well-preserved 
mid-to-posterior caudal vertebra, the partial centrum of 
a distal caudal vertebra, a complete pneumatic anterior 
dorsal rib from the right side, the nearly complete left 
scapula of a much larger, presumably adult, individual, 
and two partial sternal plates. Brontomerus is diagnosed 
by five autapomorphies of the type specimen: 
preacetabular lobe 55% of total ilium length, longer than 
in any other sauropod; preacetabular lobe directed 
anterolaterally at 30 degrees to the sagittal, but 
straight in dorsal view and vertically oriented; 
postacetabular lobe reduced to near absence; ischiadic 
peduncle reduced to very low bulge; ilium proportionally 
taller than in any other sauropod, 52% as high as long. 
In a phylogenetic analysis, Brontomerus was recovered as 
a camarasauromorph in all most parsimonious trees, but 
with uncertain position within that clade. The large 
preacetabular lobe of the ilium anchored powerful 
protractor and abductor muscles, but precise 
interpretation is impossible without functionally related 
elements such as femora and proximal caudal vertebrae. 
Brontomerus is the eighth sauropod genus named from the 
Early Cretaceous of North America, and more remain to be 
described: North American sauropod diversity did not 
decline catastrophically at the end of Jurassic as often 
assumed. The most striking differences between Late 
Jurassic and Early Cretaceous sauropod faunas in North 
America is that the former are abundant and dominated by 
diplodocids, whereas the latter are comparatively scarce?
though still diverse?and dominated by macronarians.

======
The paper has great reconstruction of a parent 
Brontomerus defending a youngster by kicking the 
Cretaceous out of a
Utahraptor.