[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]
Re: Third claw for climbing was Re: Pro(to)avis
David Marjanovic wrote:
Again this depends on the orientation of the feathers. If they are all in
parasagittal planes, there isn't going to be much of an effect...
For the purposes of drag, I'm not so sure the precise orientation is
But I've never liked the Pouncing Proavis idea, for other reasons. It
requires a rather small animal (if it's too heavy, feathered fringes won't
have enough of an effect).
To put the Pouncing Proavis hypothesis in it historical context, it was
proposed at a time when _Caudipteryx_ was thought to be very close to the
origin of birds. Now, we have _Microraptor_ and possibly _Pedopenna_, both
of which are closer to the base of the Aves than either _Protarchaeopteryx_
and _Caudipteryx_ (both of which are falling out as basal oviraptorosaurs).
Microraptorans and _Pedopenna_ offer alternate ecomorphologies for
pro-avians. Then again, these four-winged gliders may have been an
evolutionary dead-end and are just muddying the waters when it comes to
reconstructing the origin of avian flight.
Then it requires pretty large prey, because small prey is unlikely to stand
still (within a sufficiently small area at least) for long enough that an
incipient Pouncing Proavis would have any chance.
It think this is a slight oversimplification. The 'pounce' may get the
Proavis close to the prey, and it could run over the intervening distance
with those cursorial hindlimbs.
I prefer separate explanations. Wings for brooding, then exapted for... who
knows... WAIR or maybe even swimming or...
Swimming, a la Ebel's swimming-to-flight hypothesis? It's an interesting
model... but, nah, don't think so. :-)