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Re: Alamosaurus as biggest North American sauropod



From what I understood in the paper, here is the reasoning of the authors for 
assigning these three bones to *Alamosaurus*:

- Late Cretaceous sauropods are all titanosaurians

- cervical vertebra with wide cotyle =>  as in *Alamosaurus*, *Malawisaurus*, 
and *Puertasaurus*

- cervical vertebra with lateral pneumatic fossae =>  as in *Alamosaurus*, 
*Rapetosaurus*, *Malawisaurus*, and *Saltasaurus*

- no relevant feature on the caudal vertebra and femur

- no evidence for more than one sauropod taxon from the Maastrichtian of US

"We therefore refer the new specimens to *A. sanjuanenis*, based on
stratigraphic and geological parsimony, and the similarity of SMP
VP−1850 to cervical vertebrae from Texas (Lehman and Coulson 2002), and
SMP VP−1625 to the caudal series from Utah (Gilmore 1946)."

Stratigraphic and geological parsimony ?! WTF, if I may say so !

I recognize that these remains are indeed very interesting for indicating the presence of a giant 
sauropod in the Maastrichtian of the US and their possible belonging to *Alamosaurus*, but I think 
the authors are too much optimistic, taxonomically speaking. No need to be a specialist to 
understand that they belongs likely to a titanosaurian but there is no positive evidence for its 
assignment to *Alamosaurus* - and if stratigraphy or geology were taxonomically relevant, we would 
know it ! Hell, there is not even a "cf." or an "aff." in the identification of 
the specimens. Of which two are... indeterminate titanosaurians (just read the text).

So... please, don't do that anymore.

Time to go to bed,

Jocelyn

Le 07/12/2011 18:14, Ben Creisler a écrit :

From: Ben Creisler
bscreisler@yahoo.com
A new paper in Acta Palaeontologica Polonica: Denver W. Fowler and Robert M. Sullivan (2011)
The first giant titanosaurian sauropod from the Upper Cretaceous of North 
America.
Acta Palaeontologica Polonica 56 (4), 2011: 685-690
doi:10.4202/app.2010.0105
http://app.pan.pl/article/item/app20100105.html

Argentinosaurus (Cenomanian, Argentina) is generally accepted as being the largest 
dinosaur so far discovered and is one of several giant titanosaurian sauropods known 
from the Upper Cretaceous of South America and Asia, but surprisingly not from North 
America. Here we present the first evidence of giant titanosaurian sauropods from the 
Upper Cretaceous of North America: two enormous vertebrae and a partial femur, from 
the Naashoibito Member of the Ojo Alamo Formation, New Mexico, and referred to 
Alamosaurus sanjuanensis. One of the new vertebrae, a posterior cervical, is 
comparable in size to a posterior cervical described for Puertasaurus: an 
Argentinosaurus−sized titanosaurian from the Maastrichtian of Argentina. This 
makes A. sanjuanensis the largest dinosaur from North America, and among the largest 
in the world. These findings indicate that A. sanjuanensis is diagnosed based on 
immature remains, which may have implications for cladistic analyses.