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Re: Stegosaurus

On Sun Jun 11 15:07:23 1995, Jerry D. Harris wrote:

>       We _do_ know the arrangement of _Stegosaurus_ plates, for sure, 
>now!  Tahnks to the 85% complete specimen we of the Denver Museum found 
>in '92, articulated with the plates in the correct positions, we know 
>that _Stegosaurus_ had two rows of alternating plates.  The plates in the 
>new specimen partially overlap:  if there were two parallel rows, they'd
>entirely overlap, and if there was only one row, they would only barely 
>or not at all overlap.  Second, there is a great deal of matrix between 
>the plates in the new specimen, indicating that in life they were 
>separated by a span of space.  If the animal had only one alternating 
>row, the plates would overlap only slightly, and not have such a space
>between them.  Thus, the only solution left is that they had two 
>alternating rows!

Now this is risky business -- laying out my ignorance for the entire dino
list to see is not my usual cup of tea. But I am confused by the statement
above, so, here I go.... (Please be gentle with me.)

Is the _Stegosaurus_ meant here the one found at the Garden Park site by
Bryan Small and presently being prepared by Donna Engard? If this is the
case, Greg Paul wrote a brief report on the specimen (in "Tracks in Time"
(Garden Park Paleontology Society newsletter), Spring 1992) describing the
plate arrangement and throat ossicles. He stated, "...some of the plates
were in place and staggered." And later, "The bases of the forward trunk
plates are much broader on the outer than on the inner side. This suggests
that the plates were set off from the centerline." However, his illustration
based on the same specimen (coverpiece for the Garden Park Dinosaur
Discovery Center flyer), shows the plates in (nearly) a single row -- far
closer together than the placement on the famous _Stegosaurus_ model from
the British Museum of Natural History. And, to confound the situation
further, Greg Paul also wrote, "...there might be variation in the position
of the plates in the species. Other _Stegosaurus_ seem to have retained
paired plates." So, is there a revised interpretation? When is it one row
(alternating) and when is it two rows (alternating)? I was under the
impression that the most recent interpretation was for one row of
alternating plates.

Thanks for helping clarify this detail.

Now for other business:

>From a purely aesthetic point of view, my favorite dinosaur as a child was
_Stegosaurus_, but now, as a (bearded) adult, it is _Parasaurolophus_,
particularly when interpreted with a handsome skin flap stretching from the
crest to the neck and back.  :)

 Douglas E. Goudie                  To know all things is not permitted.
 ac941@leo.nmc.edu                               -- Horace (65 - 8 B.C.)