Re: Alamosaurus as biggest North American sauropod

[Jocelyn Falconnet <j.falconnet@gmail.com>]

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.