Re: SVP Papers

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

Michael Lovejoy (michael@palaeoproductions.fsnet.co.uk) wrote:

<Mickey Mortimer wrote (quoting W. Parsons) that Deinonychus had "a strong
sagittal crest on the parietal fragment,....The sagittal crest continues
on to the frontal region on the dorsal surface of the skull. This would
create a striking feature in a life reconstruction."

Forgive my anatomical ignorance, but can someone explain what this would
look like?>

  Well, a sagittal temporal crest usually supports temporal musculature. I
have not yet seen a single animal in extant that had a sagittal crest that
did not support musculature, from gorillas to chameleons. In the case of
the latter, this is expanded out laterally at the occipital plate and
further dorsally nearly doubling the depth of the skull above the orbit
and indicates a display function, as has at one point been described for
the very large crest in male gorillas. However, these embody a lot of
muscle still and the crest is not visibile in the numerous mammals that
have very large ones from bears, primates, some cats, primitive whales,
etc.. This crest is very large but streamlined in tritylodontids and other
eucynodonts, an extreme case being *Oligokyphus.* In any dinosaur the
crest will support the deep and superficial temporal musculature, and it
is unlikely it will be exposed or its shape approximated in life as no
muscle forms a sharp edge or corner as the bone does.

  Hope this helps,

  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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