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Re: YAVERLANDIA



Joe Parish wrote:

<Are there any ankylosaurians with skull roof
thickening>

  *Gastonia burgei* is notable for having a dome-like
developement of the frontal plates; it is added to the
"dome-headed" dinosaur group as a possible head-butter
(not "ram") and a visual description of this attitude
was given in Bakker's pseudo-paper _Raptor Red_, for
those lacking the access to the paper by Kirkland,
1999. Similarly, *Majungatholus atopus* is a theropod
with a central dorsal thickening (Krause et al., 1998)
that may have served as a butting device, because I
cannot imagine this thing as a visual signal -- it
doesn't seem to correspond to such visual apparent
"signal" present in other theropods. Aside from
pachycephalosaurs, of which the basal members,
"homalocephalids" lack domes, another theropod
possesses a "dome-like" structure, *Avimimus
portentosus* (Kuzanov, 1983, 1987), in which the fused
frontals ascend apically above the front of the
orbits. Chatterjee's domes are similarly developed to
pachy domes in they they are developed highest above a
presumed posterior end, and are perfectly symmetrical;
development of supposedly lateral rims above cranial
fenestrae (but not supratemporal fenestra, which are
not apparent) are similar to *Stegoceras*, and the
domes themselves resemble those of that pachy, as
Goodwin commented at SVP. Possible palatal bones are
present, and are symmetrically arranged, so these
things are singlular, sagittal structures that may or
may not have been domes. CT scans and detailed
analysis should prove whether or not they are what
Chatterjee has suggested they are. [He is quite proud
of them, as you may well imagine, and I feel more and
more recently, many of his assumptions are proving
more and more likely...]

  <and texturing?>

  Just about every ankylosaur has "texturing." Pitting
and vascularization as in some pachycephalosaurid
skulls is known otherwise only in non-amniote
craniates, especially labyrinthodonts; ankylosaurs
sport quite rugose and knobbly to "paved" texturing
and also have a different histology to the bone than
do pachycephalosaurs.

=====
Jaime "James" A. Headden

"Come the path that leads us to our fortune."

Qilong---is temporarily out of service.
Check back soon.

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