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Re: SAUROPOD FEATHERS



Jura wrote-

> The Patagonian titanosaur embryos all show scale impressions (all the ones
that are visible that is). They were the ones I was using as evidence for
sauropod scales. I'm not sure we have any large sauropod scale impressions.

Indeed there are adult sauropod scale impressions.  Tehuelchisaurus and
"Pelorosaurus" becklessi for instance-
Gimenez (2000) describes the skin impressions of Tehuelchesaurus, which
originate from the thorax and scapular regions.  The skin is covered with
tubercular scales with two diferent patterns- semi-smooth and hexagonal
scales (3x2.5 cm) alternating with smaller ones (2x1.5 cm) in small roseate
patterns; rhomboidal scales (2-4 mm).
Gimenez, 2000. The discovery of skin impressions of a sauropod dinosaur in
Chubut Province, Argentina. JVP 20(3) 44A.

> I do think it is pertinent to mention that only maniraptors have been
found with fuzz. No other coelurosaurs have shown this. In fact, those that
have had impressions found (i.e. the tyrannosaur impressions, and yeah, I
know it's another big guy) have all shown scales. So, it would seem that
maniraptora would be the starting point for this fuzz stuff, not
coelurosauria.

Not true,  Sinosauropteryx has filaments and is almost certainly a basal
coelurosaur, outside of maniraptoriformes.  I have my doubts it's even a
compsognathid (credit for first having this idea goes to Nick Longrich, way
back in April of 2000), probably being more basal than Compsognathus.

> Is it more parsimonious to assume that this fuzz evolved convergently
between pterosaurs > and maniraptorans, or is it more parsimonious to assume
that it was subsequently lost in
> the majority of dinosaur species?

Depends on the phylogenetic position of pterosaurs, how much credence is
given to the "big species will automatically lose the feathers for scales"
theory, and which non-dinosaurian archosauromorphs are known to have scaly
skin.  Longisquama has elongate scales (not the dorsal scales), Cosesaurus
has a "dorsal frill", Sharovipterx has scales on the tail and snout, but
smooth neck skin.

Pete Buchholz wrote-

> The only under 1000kg
> > non-theropod dinosaurs with skin impressions are Liaoning psittacosaurs
which
> > are said to possess very long barbs and/or mosaic scales, neither of
which
> > have been illustrated, so I cannot comment at this time.

Suuuure they haven't Pete. :-)  I doubt any speculation we make based on the
low quality photographs available will present any harm to potential authors
of a paper describing them.  Long (~9 caudal lengths) unbranched filaments,
slightly curved posteriorly.  They don't go through the epidermis, start
behind the fourth caudal vertebra and extend to the nineteenth or so,
getting shorter posteriorly for the last several vertebrae at least.  That's
all we know.

Mickey Mortimer