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AW: Tawa hallae: everything you know about basal saurischians is wrong...
Is there any evidence for this claim?
(And has anybody ever checked GenBank whether the "feather" genes have some
sort of viral signature? A "domesticated" papillomavirus or similar would
explain the structurally different but physiologically somehow related - as
integumental hyperplasies triggered by a fairly simple genetic mechanism,
essentially - structures phylogenetically widespread among archosaurs. But its
genetic "footprint" would be obvious, and thus this assumption could be tested.)
Nonwithstanding, I find the notion of sticking feathers everywhere a bit
dubious; eventually it's likely to result in major embarrassment and a lot of
cheering from BANDits. Feathers/fuzz and large-bodied animals living in a
tropical climate and well on their way to homothermy do not at all mix well.
Phylogenetic bracketing is also unhelpful with such a limited sample of hard
evidence; _Elephas_ and _Heterocephalus_ for example would provide a nice
bracket that "proves" all mammals, big and small, are almost nude, if we did
not know as many mammals as we do.
Absence of quill knobs (and possibly rectrical knobs, which are as of yet
unknown but might conceivably have evolved as alternative to a pygostyle) in a
large-bodied non-polar non-flying archosaur, I'd presume, is strongly
indicative that the critter had no integumentary fuzz, feathers or bristles to
One thing that has not been considered: parasites. In general, the maintenance
effort of plumage is not especially light; birds spend much of their leisure
time (which can be considerable; I once had a project where I had to observe
_Ducula pinon_ as they lazed away 90% of their day time) with preening. Those
that feed on carrion more than opportunistically generally have naked heads and
possibly necks. So, a soiled plumage seems to be more trouble than it's worth.
Lacking a beak but possessing hands, nonavian theropods would likely soil
themselves while feeding more than avian ones do today. And as far as anyone
can tell, they did not have an uropygial gland, so bathing would be cumbersome
or downright hazardous (wet plumage is a problem except for those birds that
are specifically adapted to it. But it seems in the first place a problem, not
a benefit; otherwise it is hard to see why loss of waterproofing did not evolve
more often than it did).
I see no problem at all with "flight feathers" evolving prior to flight
(powered or not); in fact, there are pretty good reasons for them to do
(signalling, agility). Downy young - no true down having been found in a
nonavian context nonwithstanding - also seem good. But large theropods being
fully feathered even as adults? Everything we know about large quadruped
physiology says "not a good null hypothesis".
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