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Re: Scypionyx (Ciro) huge monography published



>> Part I deals with osteology and phylogeny. Each bone is detailed, and 
>> juvenile characters evaluated, then the classification and phylogenetic 
>> relationships are proposed (360 >characters for 95 taxa),
>> according to the authors Scipionyx is a compsognathid, the the sister taxon 
>> of Orkoraptor.




This caught me by surprise.  Novas et al. (2008) found _Orkoraptor_ to
be a compsognathid (Fig. 8B - consensus majority rule; but not in the
strict consensus tree), although in the accompanying text the authors
were cool on the idea of _Orkoraptor_ being a compsognathid.  Later,
Benson et al. (2010) recovered _Orkoraptor_ as a neovenatorid.  They
also noted that the postorbital of _Orkoraptor_ is almost identical to
that of _Aerosteon_.


If _Orkoraptor_ is a compsognathid, it's significant for two reasons.
Firstly, it would be the largest known compsognathid by far.  I've
seen body length estimates of 6-7m for _Orkoraptor_ - this is more
than double the size of _Sinocalliopteryx_ (~2.4m), otherwise regarded
as the largest compsognathid.  If _Orkoraptor_ had compsognathid-like
proportions (including a long tail), it may have had an even longer
body length (7.5-8m).


Secondly, _Orkoraptor_ is from the Pari Aike Formation, which has been
dated to the Maastrichtian.  If _Orkoraptor_ is a compsognathid, it
would make it the last known member of this group.  (In a similar
vein, Benson et al. [2010] regarded _Orkoraptor_ as the last known
allosauroid.)  Either way, and based on what little is so far known of
this theropod, _Orkoraptor_ appears to be a relict taxon.




Cheers

Tim