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RE: SAUROPOD FEATHERS
I wholeheartedly agree with George, and I certainly hope Norell
qualifies his statements by saying ornithischians and sauropodomorphs most
likely had bristle-like protofeathers (and that they probably did not cover
the whole body). If not, he is going to give some people the false
impression that they had vaned feathers like maniraptors and birds (i.e.
birds sensu Kinman) and that they were first developed for body insulation
(which I strongly doubt). And it is certainly very disturbing to see
Chinese scientists calling pterosaurs "feathered" if all they had were
As for the sauropod embryos (or ornithischian embryos for that matter),
I believe the first "bristles" would have been along the backbone and tail.
If my "protofeathers evolved on the tail first" hypothesis is correct, they
may well first appear on the tail and then spread up the spine during
I think this hypothesis may be supported by the bristle-tailed
psittacosaur. If tail bristles evolved first, then they may well have been
the last to be lost as dinosaurs got bigger. It is therefore no surprise
to me that dinosaurs had considerable portions of the bodies lacking such
protofeathers. Even once exapted for brooding, only the posterior parts of
the adult would *need* to be covered with brooding bristles. Perhaps only
in advanced coelurosaurs did they spread to arms and eventually become
exapted for aerodynamic functions.
---- Cheers, Ken Kinman
P.S. As for Longisquama, its paravaned parafeathers may well be homologous
to protofeathers, but they are pretty clearly convergent on real vaned
feathers found in Class Aves (sensu lato).
For some time now I've suspected (and argued) that all dinosaurs had
feathers of some kind--perhaps not like those of modern birds but certainly
homologous keratinous dermal structures. These might occur quite far down
the archosaur clade and could well be homologous with pterosaur "hairs" and
even Longisquama "wings." Nice to know that there might actually be some
hard evidence for these.
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