Re: Paedomorphosis ( Re: BARYONYX' CLAWS )

[Dinogeorge <Dinogeorge@aol.com>]

In a message dated 98-04-11 22:08:49 EDT, m_troutman@hotmail.com writes:

<< The form of secondary flightless that I argue against is the flightless 
 is the one where some theropods had volant ancestors that went 
 flightless. Since they lack the paedomorphic trends seen in birds, it 
 seems unlikely that they had volant ancestors. I think that we have come 
 to an understanding ( at least it seems so ). I think that it sounds 
 that you you agree that no theropods had volant ancestors ( at least it 
 sounds like that ) because they lack the paedomorphic trends see in 
 flightless birds.  >>

Right, if by volant you mean "capable of powered, flapping flight." There are,
however, theropod lineages that diverged from the avian lineage quite close to
the point from where _Archaeopteryx_ diverged--such as dromaeosaurids
(including _Rahona_, which has the kinds of wings I and I'm sure Greg Paul
before me envisioned for flying dromaeosauroids), alvarezsaurids,
parvicursorids, oviraptorids, _Unenlagia_, and such. These could well have had
>volant< (by your definition) ancestors that resembled _Archaeopteryx_ in
their flight capabilities. However, since we do not have a handle on just what
kind of flying _Archaeopteryx_ did (whatever kind it was, it must have been
different from that of modern avians, if only because of the aerodynamic
properties of the elongate tail and the lack of a giant keeled sternum), we
just have to wave our hands at this point. "Volant" it probably was, but just
how volant remains a matter of conjecture.

Meanwhile, I'm going to take a closer look at the idea that carnosaurs might
after all have been paedomorphic descendants of small, arboreal theropods.
It's worth some thought, although at this point I can't see how one might do
anything more than assert it was possible.

Also--how about _Hesperornis_? Flightless by paedomorphosis? (Don't think
so...)