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Re: MOSASAUR CRESTS AND SKIN



On 96-04-19 13:58:21 EDT, Darren Naish wrote:

>I wonder if anyone could help me with some queries on the life appearance of
>mosasaurs.

>Ever since Charles Knight, it's been the norm to illustrate mosasaurs with a
wavy skin >crest going along the backbone, a bit like that you find in some
modern >lizards...Lingham-Solaire's historic review of mosasaurlocomotion
includes a quote >from a Samuel Williston paper from 1894 or thereabouts in
which he recognised these >structures as preserved displaced cartilaginous
rings from the trachea. Where does >that leave the 'crest'? Is there any
evidence for it in any fossils?

Funny you should ask.  I asked Dale Russell this very question at Dinofest
last weekend.  He agreed that the so-called "crest" was displaced tracheal
cartilege, and he was not aware of other evidence of nuchal fringes.  I'd
asked the same question of mosasaur expert Gordon Bell at the last SVP
conference, and he said the same thing.  Sounds like the mosasaurs were
hydrodynamically sleek like orcas or seals, and weren't the scaley sea
monsters as they are sometimes portrayed.

>I've read (it's on the NG Dinos of N. America poster I think) that mosasaur
skin >impressions are known, and reveal small, diamond-shaped scales. Is
anyone aware of >any reference describing these impressions?

Check F.H. Snow's "On the Dermal Covering of a Mosasaurid Reptile" in the
Transactions of the Kansas Academy of Science.  He describes the scales of a
Tylosaurus as being very similar to the diamond-shaped scales of a
rattlesnake - except smaller.  Only 3.3 mm long and 2.5 mm wide.

BTW, at Dinofest, Bob Bakker said that the skins of ichthyosaurs and
plesiosaurs he's examined is completely smooth to the naked eye.  Hope this
helps.

Gary Kerr