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Re: Fwd: RE: T. rex Predation



Mickey Mortimer (Mickey_Mortimer111@msn.com) wrote:

<I'd like to see your evidence for large Deinonychus' Jaime.>

  Wrong question. Best to ask for the comparison, not a large
*Deinonychus*, or a clarification of why i said what I did (you did not).
Rather, ask why I suggest *Achillobator* isn't that large. Femur size is
unimportant; unlike *Deinonychus*, *Achillobator* has a short foot and
shin relative to femur size and the overall hip height was about 20cm
higher. The trunk and neck, by examining of the vertebral lengths, are
relatively much shorter, and its not just a scaling up from femur size,
because this misleads. The over all animal based on general vertebral
counts of maniraptorans based on *Deinonychus* (in part) gives an estimate
just shy of 4m. This includes a tail almost twice as long as the
pre-caudal sequence and skull. The skull itself suggests a shorter, less
"velociraptorine" appearance, and the vertebrae being shorter, higher, and
more "oviraptorosaur" like imply a stocky, short, and maybe chunky-looking
animal.

  As an aside, and as I beleive I wrote last year on the list, Allain and
Taquet used various data based on the so called validity of relation of
the material used to support *Variraptor* as being erroneous and are
referring to the taxon as a _nomen dubium_ because of the material may
belong to an oviraptorosaur. Problematically, *Achillobator* does as well,
and as I discussed on the nature of a chimaera, this either implies
*Achillobator* is a chimaera, *Variraptor* is valid, or the authors should
have been much more cautious about applying a variety of maniraptoran
bones from Vaches Noire to a single taxon, *Pyroraptor*.

  Nonetheless, large *Deinonychus* are notable based on shed teeth from
the Cloverly, larger than known skull material supports by around 10-15%.
This gives a 10ft or so length general upper size, and close to the 12-13
ft length I estimate for *Achillobator* for me to suggest they were about
the same size, generally. Thouigh chunkier relative to length, the two
animals had similar pre sacral lengths based on the AMNH and YPM material,
and *Achillobator* was certainly heavier, but much of the length
differential is likely based on what appears to be a fairly longer tail,
and this is based on exagerrating a count to around 40-45 verts. 

<Utahraptor's 10+ meter length isn't large enough for you?>

  And where is THIS data coming from?

  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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