[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]
Re: Origin of feathers
<< Name me a bird that broods with feathers on the lateral surface of
the body. While not disparaging the idea that yes, the brooder could
have had brooding feathers on the sides, it is not unpresumptuous to say
that yes, there could have been brachial feathers long enough to brood
with, and even not interfere with the other manual or brachial motions
of the arms. >>
<You're missing my point here.>
Perhaps. I think I may have been a little testy when I wrote this (not
at you, or anything on the list, a perfect example of letting my life in
the back door).
<I would assert that there are no lateral brooding-feathers in birds
because they make use of the feathers that appeared on their forelimbs
for reasons other than brooding. When you assert that feathers appeared
in birds >for brooding eggs<,>
I didn't say that. I was actually agreeing with you. I went on to say
that feather evolution as functional flight may have been exapted for
the brooding method in *Oviraptor*.
<you haven't explained why they would appear preferentially on the
forelimbs and not somewhere else, such as the sides of the bird or the
back, etc. You need to come up with something about the forelimbs that
would compel the evolution specifically of brooding-feathers there, to
the exclusion of other parts of the body.>
I would assume they would appear on the forelimbs because Ovi's
ansectors had them, albeit being a little smaller, having a smaller
brood to care for, even a single egg. Those wings of Archie sure would
make excellent sunshades :-) If anything, the posture of the brooder
actually agrees with BCF, wouldn't you concur? And if feathers appeared
on the forelimbs, long and secondary-like, why not? Of course, why?
Hot sun, for one, and the environment wasn't to moist. Ostriches
"parasol" their wings over both egg and chick, as do rheas and emus;
cassowaries, being tropical jungle dwellers, just build mounds of dirt
and sit around all day. These wings (or should I say, feathers?) have
stuck around, even with the flight capability gone. I'm just saying that
Ovi suggests this as well.
<< Many birds can adjust their feathers so they do not stick out, lay
flat, etc. The ventral surface of the avian ulna is ridged, while
*Oviraptor*'s (for instance) is not, and we already assume Archie could
use his claws and fly (or ornithopt, or whatever). The ridge actually
stiffens the quills, while a rounded surface would not provide any
direct anchor for the ends. Thus, we can assume that a brooding dinosaur
could actually tuck its feathers parallel to the arm, and never
interfere with the manual motions. >>
<This is actually a pretty strong argument against the existence of
>any< sizable wing feathers on the forelimbs of _Oviraptor_. Perhaps we
should consider whether _Oviraptor_ retained any feathers at all, let
alone elongate brooding-feathers of some kind. Perhaps _Sinosauropteryx_
fuzz is all the feathers _Oviraptor_ had, too.>
If this _is_ so, how do we then look at the arm posture? This could
have been taphonomical, but when we see this, and compare to a bird
brooding, we are instantly astounded. The AMNH sure was. The
similarities are just staggering.
Now, aside from the visually-blinding standpoint, could we assume that
yes, long feathers existed on the arms, long enough to cover the spaces
between arms and feet where eggs are exposed? Fuzz, or bare skin would
not do the job, as exciting an idea it might actually be.
*Sinosauropteryx*, for instance, may have used his fuzz (quite long on
the sides and arms) to maximize the lateral plan of coverage. Later on,
Archie has feathers, and his sister group gives rise to oviraptors, and
they retain the [Archaeopteryx + Oviraptor] arm feathers.
Anyway, the Djadochta doesn't seem to be very good at preserving
impressions, such as Santana, Solnhofen, Las Hoyas, or Yixian beds. We
may have to wait a while to see the evidence for, and if it doesn't
appear, that could mean it may not exist.
I don't disagree with you, George.
Jaime A. Headden
Get Your Private, Free Email at http://www.hotmail.com