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Re: Follow-up: the truth about killer dinosaurs

T. Michael Keesey wrote:

I get tired of hearing this excuse for artists to maintain the
"classical" view of tyrannosaurid integument.

I guess it may depend upon the "tyrannosaurid" (or "tyrannosauroid") in question. Tyrannosaurid skin impressions from Canada show a more-or-less "classical" scaly integument, so this may be typical for the big-ass Late Cretaceous tyrannosaurids. But _Dilong_, a smaller and more primitive relative, shows those new-fangled feathers (or precursors of feathers). Feathery-ness in theropods may be a consequence of many factors: size, climate, seasonality, age...

On that last one, juvenile _T. rex_ might have been endowed with natal down, which was shed from most of the body as the creature got older and bigger, as Mike suggests...

And is the analogy completely valid? Tyrannosaurids, like all
archosaurs, hatched from eggs, and so began life well within the size
range of animals which insulation can benefit. Perhaps they became
less fuzzy as they grew (indeed, elephants are born somewhat hairy,
then lose the meager fuzz), but is there any reason to suspect it
fully disappeared?

Perhaps adult _T. rex_ had fuzzy eyebrows, sprouting from those peculiar lacrimal crests. :-) We know that many non-coelurosaurian theropods show elaborate cranial crests made of bone - so why not decorative crests made of feathers in the coelurosaur groups? At least one _Microraptor_ specimen shows a mane-like crest - why not _T. rex_?