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SAUROPOD FEATHERS



archosaur@reptilis.net wrote:
<<Fascinating; we have scale impressions from theropods, sauropods, ceratopians and hadrosaurs. We have "feather" impressions of only a few theropods, all of which are maniraptors.>>

True kind of.  We have skin impressions of theropods, sauropods and ornithischians that exceeded 1000kg that show mosaic scales.  We have skin impressions from only a few dinosaurs under 1000kg, most of them coelurosaurs, all of them with dinofuzz or feathers.  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.

It is not a huge leap to hypothesize that perhaps the long barbs on the psittacosaurs are feather homologues.  This needs to be tested morphologically and chemically.

<<It reminds me of his video presentation at the AMNH near the _Oviraptor_ skeleton, where he adamantly states that this _Oviraptor_ was proof positive that birds were dinosaurs, because this animal died while sitting on its nest like certain lizar..I mean birds do.>>

I am not sure what you're getting at here.  Are you suggesting that birds are not derived thereopods?  Or are you simply stating that the brooding position of Oviraptor, which is a behavioral trait, has a much larger phylogenetic range?  I don't think that second [nor the first honestly] is going to have much data supporting it.

<<So, has Norell *seen* the Patagonia sauropod embryos?
.......
That, and the embryonic sauropods have preserved SCALE impressions.>>

Embryos have scale impressions?  I have always been somewhat skeptical of this claim for quite a few reasons.  First of all, most of the scale impressions appear outside of the nests, and are completely haphazard around the nesting site.  These are most likely the impressions of adults walking around the nesting grounds.  Secondly, almost all of the eggs are broken and possibly trampled, and scale impressions within the nest could be those of adults manipulating eggs, or older juveniles.  Maybe sauropods never had dinofuzz on their legs?

Maybe my hypothsis is wrong.  What I am saying though is that I believe that the hypothesis that the scale impressions belonged to the embryos themselves is not the only possible explanation of the data available.

Pete Buchholz
Tetanurae@aol.com