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RE: Neovenatoridae and Megaraptora: now it can be told!



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Tim Williams wrote-

> Longrich and Currie (2008=3B the _Albertonykus_ paper) also poor cold wat=
er on the idea that _Rapator_ is an alvarezsaur. Oh well. Given the size of=
 the element=2C _Rapator_ would have been quite a large alvarezsaur=3B but =
now it's just a fairly average-sized megaraptoran.
>
>
> The type material for _R. ornitholestoides_ is a solitary metacarpal (mc =
I)=2C which does not appear to be diagnostic at the=20
> species level. So the species is presumably a nomen dubium. Therefore=2C =
although it is possible that _Austalovenator_=2C=20
> _Rapator_=2C and _Walgettosuchus_ all represent the same theropod species=
=2C there is fortunately no danger of _Australovenator_=20
> (which is based on good material) being sunk as a junior synonym of _Rapa=
tor_.
=20
First=2C even if it is a megaraptoran (which hasn't been shown AFAIK)=2C Ra=
ptor is different from Australovenator. Hocknull et al. wrote "The Mc I of =
Australovenator wintonensis is larger than to that of the Rapator ornithole=
stoides holotype=3B is missing the prominent caudomedial process projecting=
 proximo-dorsally=3B possesses more subequal distal condyles=3B a flat prox=
imal articular surface compared to the concave surface in R. ornitholestoid=
es=3B and a straight distal lateral condyle compared to a disto-laterally p=
rojecting distal lateral condyle in R. ornitholestoides." Furthermore=2C Ra=
ptor has not been shown to be identical to any other theropod species=2C so=
 is not a nomen dubium.  It may just be a metacarpal I=2C but it's a distin=
ctive metacarpal I.  That posteromedial process in particular has been sugg=
ested to be diagnostic=2C though Gishlick and Gauthier (2007) did suggest a=
 similar structure was diagnostic of compsognathids.  Salisbury et al. (200=
7) compared Rapator to Nqwebasaurus=2C which has the compsognathid-style pr=
ocess if I recall correctly=2C indicating a direction for future research.
=20
Mickey Mortimer
The Theropod Database- http://home.comcast.net/~eoraptor/Home.html









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----------------------------------------
> Date: Tue=2C 20 Oct 2009 16:43:47 -0700
> From: tijawi@yahoo.com
> To: dinosaur@usc.edu
> CC: tijawi@yahoo.com
> Subject: RE: Neovenatoridae and Megaraptora: now it can be told!
>
>
> Thomas R. Holtz=2C Jr. wrote:
>
>
>> I have published (in Dinosauria II) my speculation that
>> Rapator is a giant
>> early alvarezsaurid. However=2C now that I have a cast of the
>> specimen=2C and
>> with the information of megaraptorans in hand (as it were)=2C
>> I reject my
>> earlier speculation and much more strongly support Rapator
>> as a basal
>> tetanurine=2C possibly a megaraptoran.
>
>
> Longrich and Currie (2008=3B the _Albertonykus_ paper) also poor cold wat=
er on the idea that _Rapator_ is an alvarezsaur. Oh well. Given the size of=
 the element=2C _Rapator_ would have been quite a large alvarezsaur=3B but =
now it's just a fairly average-sized megaraptoran.
>
>
> The type material for _R. ornitholestoides_ is a solitary metacarpal (mc =
I)=2C which does not appear to be diagnostic at the species level. So the s=
pecies is presumably a nomen dubium. Therefore=2C although it is possible t=
hat _Austalovenator_=2C _Rapator_=2C and _Walgettosuchus_ all represent the=
 same theropod species=2C there is fortunately no danger of _Australovenato=
r_ (which is based on good material) being sunk as a junior synonym of _Rap=
ator_.
>
>
> Cheers
>
> Tim
>
>
>                                         =