Re: Follow-up: the truth about killer dinosaurs

["T. Michael Keesey" <keesey@gmail.com>]

On 8/31/05, Denver Fowler <df9465@yahoo.co.uk> wrote:
> 
> but that said there is no
> fossil evidence of T. rex having integument, and I
> would argue that it was rather a large animal to have
> required any sort of insulation. You might expect the
> opposite in fact.

I'm going to go on a little rant here. Nothing personal—it's just that
I've heard this *so* many times.

I get tired of hearing this excuse for artists to maintain the
"classical" view of tyrannosaurid integument. There's no fossil
evidence for _Ichthyornis_ having feathers, or _Patagopteryx_ or
_Gargantuavis_ or _Rahonavis_, but no artist would dream of seriously
restoring any of them as scaly. (Although Brad McFeeters did make a
lamppon at my suggestion:
http://img.photobucket.com/albums/v222/Bradysaurus/sketches/patagopteryxneuquenornis.jpg)
But the evidence for these Mesozoic coelurosaurs being feathered is
just as good as for tyrannosaurids.

Many people use the "large pachyderms are naked" argument, but what's
our sample size? Less than a dozen species, one of which is
amphibious, and two of which had amphibious ancestry (albeit remote).
Furthermore, none of them are completely naked—long hair remains in
eyelashes and in tails (except _Hippopotamus_). And then there are
extinct species from colder climes which were emphatically not naked.

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?

Furthermore, feathers and hair are not the same things. Might it be
that feathers, which tend to be stiffer and more mobile, are not as
prone to overheating their bearers as hairs are? What do we see in
large feathered animals? Unfortunately the largest we have is
_Struthio_ at a mere 300 lbs. It does show some reduction of
feathers—the legs are bare, and the neck and head have reduced
feathers. But the rest of the body is not only covered, but covered in
rather long plumage. And these live in some of the hottest areas on
Earth. Other ratites (which are admittedly smaller) retain a fairly
normal amount of plumage.

Would a 5-ton ostrich be overheated by its feathers? Maybe, but has
anyone done the research to show this? And, even if it were shown, is
there any reason to think it could not simply reduce its plumage (as
on the head and neck) rather than discard it entirely? And would the
feathers be replaced by scales?

It really seems to me that the whole "_T. rex_ was too big to have
feathers" argument is mere hand-waving in support of retaining our
beloved scaly Rex. Until more research is done, or more discoveries
are made, it seems more scientific to me to assume that they were
feathered, although plumage may have been reduced in adults—but maybe
not, who knows? In any event, fully scaly _T. rex_ should have died
out in the '90s.

This is one of my favorite images of _T. rex_:
http://dino.lm.com/images/display.php?id=2728
Not only does it look like an animal, not a monster, but the plumage
is consistent with what we know about animals in that phylogenetic
bracket. (Okay, remiges on the forelimbs might be too much, but....)

—Mike Keesey