2 become 1?

["Claudio Angelo" <cmonteiro@folhasp.com.br>]

Hi there,

I've been looking at the original Angaturama and Irritator papers, plus a
note in Science (1998) in which Paul Sereno suggests that both may be "the
same taxon, or even the same specimen". Is there a consensus among
paleontologists that Angaturama is a synomymy case? I've read somewhere in
the list that I. challengeri's skull is being rewroked. By who? Could any of
you provide any contact info for the authors?

TKS,
Claudio

-----Mensagem original-----
De: Jaime A. Headden <qilongia@yahoo.com>
Para: dinosaur@usc.edu <dinosaur@usc.edu>
Cc: gorgosaur@hotmail.com <gorgosaur@hotmail.com>
Data: Terça-feira, 4 de Dezembro de 2001 16:45
Assunto: Re: 2 become 1 (spinosaurian & titanosaurian)


>Øyvind M. Padron (gorgosaur@hotmail.com) wrote:
>
><What are the actual possibilities for Nemegtosaurus to be the head of
Opisthocoelicaudia and
>Angaturama to be the snout of Irritator? Both cases seems pretty obvious,
so there must be some
>other kind of evidence keeping them apart as separate genera?>
>
>  As the situation with *Irritator* is quickly becoming resolved
(*Angaturama* is a nomen dubium
>because the snout probably comes from *Irritator* and not a sunk taxon
until you can _prove_ the
>synonymy), I'll just jump on to the other two, which I've spent some time
looking at.
>
>  For one, *Opisthocoelicaudia*, but it's anatomy, appears to be an
advanced titanosaur, though
>the caudal morphology has me stumped, as there appears to be succession in
titanosaur caudals to
>become progressively caudally ball-like on the centrum, becoming most
derived in the
>titanosaurids. In all other features, the skeleton is diagnostically
titanosaurid. The problem
>here is *Nemegtosaurus*. The skull resembles that most particularly of
*Rapetosaurus*, and in that
>paper (Curry-Rogers & Forster, 2001) *Opisthocoelicaudia* and
*Nemegtosaurus* occupy two different
>parts of the tree, not together, and the latter nests with *Rapetosaurus*.
The postcranial anatomy
>of *Rapetosaurus* does not in any specific way resemble that of
*Opisthocoelicaudia*, and there is
>such a distinctiveness its incredible. It seems improbably therefore that
the two may actually be
>congeneric. Though certainly, the matrix could be wrong. So I looked at the
skeletons themselves
>(well, through photos and published figures) and found that there are so
many differences between
>*Opisthocoelicaudia* and *Rapetosaurus* that if the skull of
*Nemegtosaurus* really does indicate
>a "rapetosaur" type (i.e., *Rapetosaurus* is a nemegtosaurid) then there is
no way that the two
>Mongolian taxa are the same animal. There is some fuzziness in this, but
the data appears to be
>pointing to two different titanosauroids in the same horizon (like, that
hasn't happened before --
>and look at the Morrison!)
>
>
>=====
>Jaime A. Headden
>
>  Little steps are often the hardest to take.  We are too used to making
leaps in the face of adversity, that a simple skip is so hard to do.  We
should all learn to walk soft, walk small, see the world around us rather
than zoom by it.
>
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