Re: Allosaur cladogram

["Jaime A. Headden" <qilongia@yahoo.com>]

Tommy Bradley (htomsirveaux@mybluelight.com) wrote:

<Oh, yeah, stupid me.  Sorry everybody.>

  Why are you sorry? Shouldn't be. This list isn't about stupid vs smart,
its about sharing and questions. As Dan said, geography Now and THEN were
different, and one simply can ask what the set up then was like. It gives
you the opportunity to learn.

  Anyways,

  *Acrocanthosaurus* finds itself as an allosaurid, closer to
*Allosaurus*, in various Holtz analyses, and this in the absence of any
real carcharodontiform features, even to the absence of the wrinkles on
the teeth. In the same analysis by Garrido and Coria on *Giganotosaurus*'
braincase, the braincase of *Acrocanthosaurus* is more similar to
*Allosaurus* than to either *Carcharodontosaurus* or *Giganotosaurus*;
this on top of the pelvic features Holtz recovered. Carcharodontosaurids
are united primarily on caudal anatomy, and while *Acrocanthosaurus* has
large lateral caudal pleurocoels, *Giganotosaurus* lacks these [to my
knowdlege, seeing the verts in poor photos and moving camera angles is
hard to allocate precise details, just general ones]. Other allosauroids
have combinations of caudal and pelvic features with more basal tetanurans
and each other that implies a basal "mosaic" of characters and a possibly
step-wise evolution towards Coelurosauria in which traditional (i.e.,
sensus Sereno et Holtz) Allosauroidea or Carnosauria is polyphyletic.
Carnosauria, Allosauroidea, and Allosauridae may all be the same clade
under some topologies.

  Cheers,

=====
Jaime A. Headden

  Little steps are often the hardest to take.  We are too used to making leaps 
in the face of adversity, that a simple skip is so hard to do.  We should all 
learn to walk soft, walk small, see the world around us rather than zoom by it.

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)

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