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Re: Megalosaurs



On Thu, 30 May 1996, Tim Williams wrote:

> Tom Holtz wrote:
>  
> What about other so-called megalosaurids like _Proceratosaurus_, 
> _Marshosaurus_, _Metriacanthosaurus_, _Xuanhanosaurus_ (which, I 
> think, has massive forearms and shoulders like _Torvosaurus_).

Of these only Xuanhanosaurus has any chance of being a true
megalosaurid.  Marshosaurus certainly is not, it is fairly clearly an
avetheropod, having an elongated pubic peduncle on the illium, a
modest sized pubic boot, and an open obturator notch on the pubis. It
is not a coelurosaur as it has a long ischium with a rectangular
obturator process, so it is either a carnosaur or a basal
avetheropod. I think it is probably a sinraptorid carnosaur because it
has (I think, though i'll have to drag out the description to make
sure) two openings to the maxillary sinus within the antorbital
fossa. Metriacanthosaurus is probably too fragmentary to tell, though
Greg Paul certainly thought it was close to the sinraptorid
Yangchuanosaurus in PDOTW. If Greg was right about the relationship
between Proceratosaurus and Ornitholestes is correct then
Proceratosaurus would be the oldest known coelurosaur (Shuvosaurus
notwithstanding).
  
> One source (I think it was Lambert's _Ultimate Dinosaur_) listed
> _Piatnitzkysaurus_ as an abelisaurid.  Any comments?

It isn't. Abelisaurids are ceratosaurs, Piatnitzkysaurus is a
tetanuran, albeit a primitive one. For example it has the tetanuran
character of a fenestra in the antorbital fossa, opening into the
maxillary sinus.

> By the way, the paper on _Carcharodontosaurus_ and _Deltadromeus_
> mentioned that at an abelisaur had been discovered in Africa.  Does
> anyone have the details?

Maybe they were talking about the Madagascan, Majungasaurus
crenatissimus.
 
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