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MOSASAUR SKIN UPDATE



(From our beauty correspondent)

Last night I read Larry Martin and Bruce Rothschild's classic paper
'Paleopathology and diving mosasaurs'. They suggest that _Platecarpus_, the
stocky, short-bodied mosasaur in which avascular necrosis was most common, was
a deep diver - it is interesting that skin impressions are consistent with this.
They mention smooth scales known to belong to this genus (presumably an
adaptation to reduce hydrodynamic drag). They compare this to diamond-shaped,
keeled scales known from _Tylosaurus_. Judging from the scales, _T_ wasn't as
adapted for diving, but there is evidence that it did so occasionally (fossils
of _T_ have been recovered in association with 9 m deep-water giant squid). This
isn't surprising, given that many pelagic cetaceans have been recorded diving
very deep.

> 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.

Artists take note! One of the exceptions to the Knightian image of mosasaurs was
Rudolph Zallinger - the mosasaur in his mural is smooth skinned and crestless.

Thanks to Gary Kerr, Tony Thulborn and Tracy Ford for refs.

> 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.

Now this is very interesting, and brings me on to something else I've been
meaning to ask. Has Bakker published any work on marine reptiles, does he plan
to? Some of you may have noticed that I referred to the 'Pliosauridae' a while
back: I've yet to see pliosaur monophyly demonstrated without doubt (and what
I've seen so far makes me doubt it). Colin McHenry has told me that Bakker
suspects polyphyly of the group also. I'm guessing this is all through pers.
comm., but does anyone know any better?

"They are forced to call everything by long names now, because they have used
up all of the short ones, ever since they took to making 9 species out of 1"
Kingsley 1863

DARREN NAISH