RE: Megaraptor question

[Tim Williams <twilliams_alpha@hotmail.com>]

Tommy Bradley wrote:

> If I might just chip into this discussion, as _Megaraptor_ is Argentinean, 
> is it possible that the material belongs to a previously estalbished South 
> American Spinosaur, such as _Irritator challengeri_ or _Angaturama limai_?

It's possible... but highly doubtful.  _Megaraptor_ comes from the 
Portezuelo Formation, which is dated to Turonian-Coniacian.  The Santana 
Formation, which yielded _Irritator_ and _Angaturama_, is older 
(Aptian-Albian).

No cranial evidence is currently described for _Megaraptor_, so there is no 
overlapping material for _Megaraptor_ and _Irritator_/_Angaturama_.  
Although around 80 teeth were collected during the excavation of the 
referred material, Calvo et al. (2005) are reluctant to refer any of these 
teeth to _Megaraptor_.  The theropod teeth that match the size of 
_Megaraptor_ have "wrinked enamel" like the teeth of carcharodontosaurids, 
and differ markedly from the teeth of spinosauroids.

Spinosauroid skeletal remains have been described from the Santana Formation 
of Brazil by De Souza-Bittencourt and Kellner (2004).  These MIGHT belong to 
_Irritator_ and/or _Angaturama_.  Although there is no compelling evidence 
to suggest that _Megaraptor_ is referrable to a previously named 
spinosauroid genus, the odds are much shorter that _Irritator_ and 
_Angaturama_ are the same animal (and, therefore, that _Angaturama_ is a 
junior synonym of _Irritator_).

> And on a more personal note, I'd like to say "Hi" again to everybody out 
> their.  It's nice to be back on the DML after a year of only getting dino 
> info from highly brevid (and speculative) CCN news blurbs.

Welcome back.


Tim