Re: Allosauroid cladogram

["Mickey Mortimer" <Mickey_Mortimer111@msn.com>]

Alessandro Marisa wrote-

> Using their previous analysis (Currie e Carpenter 2000) Coria and Currie
> (2002) in describing the Giganotosaurus's braincase performing a new
> analysis adding 15 new braincase's characters and obtain an interesting
> result: Sinraptor, Carcharodontosaurus, and Giganotosaurus form a
> monophyletic group in which Sinraptor is the sister taxon to a
> Carcharodontosaurus+Giganotosaurus clade.

I'd be wary regarding Currie and Carpenter's (2000) analysis.  I briefly
commented on this earlier, but looked into it in more detail a few months
back.  Here's what I found-

Currie and Carpenter found Acrocanthosaurus to be an allosaurid, but of
their thirteen characters supporting this, at least four are primitive
(promaxillary and maxillary fenestrae; axial intercentrum subparallel to
axis ventral margin; paired anterior and posterior processes at base of
chevrons; pubic foramen present in distal pubis), three are also found in
Giganotosaurus (basioccipital participates in basal tubera; distal ends of
paroccipital processes below foramen magnum; internal carotid opening
pneumatized), one in Carcharodontosaurus (separation of trigeminal nerve
branches complete), and five aren't known in Carcharodontosaurus or
Giganotosaurus (long basipterygoid processes; reduced external mandibular
fenestra; pronounced notch between acromion and coracoid; sigmoidal humerus;
metacarpal IV absent).  So there are actually no characters published by
Currie and Carpenter that support placing Acrocanthosaurus in the
Allosauridae.  Giganotosaurus and Carcharodontosaurus are clearly more
closely related to each other than Acrocanthosaurus is to either, but
there's no reason to believe the latter is not carcharodontosaurid.

Mickey Mortimer