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Re: theropod crests



Jordan Mallon (j_mallon@hotmail.com) wrote:

<Although _Cryolophosaurus_ and _Monolophosaurus_ are both known for their
odd cranial crests, I have yet to see a reconstruction of either of their
crests in anything but lateral view.  Have any images of the crests been
published in anterior view, preferably?  It's hard to get a feeling for 
their shape and size in only one dimension.>

  Well, I have seen the former, and the latter is illustrated so that the
crest is seen in section. *Cryolophosaurus'* crest is fan shaped and
extends laterally in a triangular aspect. I have no idea when further work
on this taxon will be done, it would make a great paper for JVP to
illustrate the large theropod material from the Mt. Kirkpatrick site or
the Elliot Formation. As for *Monolophosaurus*, the crest is triangular in
cross-section, but very broad, from rostrum to just in front of the
orbits, and narrows at the vary caudal end to a mediolaterally flat plate
braced by the dorsally projecting lachrymals. These are horns that are
appressed to the lateral surface of the crest. The interior crest is
hollow, with a chamber within separated from the nasal passage below, but
confluent caudally and entered into primarily by the two large lateral
"fenestrae" above the antorbital fenestra (one may or may not be the
lachrymal foramen). The crest of *Cryolophosaurus* is formed from the
nasals, and there appears to be a foramen between them at the base.
Imagine the lateral edges in front of the lachrymals form elongate
rostrocaudal ridges that become broader, and then "turn" sideways and
expand into a fan shape. Cryolophosaurus also have lachrymal horns, or
little "spikes" the straddle the base of the crest. *Monolophosaurus*' are
flat.

  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.

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