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Re: Paleo Find ("Millennium Man")



On Fri, 5 Jan 2001 22:49:45   
 David Marjanovic wrote:
>HP Steve Brusatte wrote:
>
>> >        *Microraptor* is significant, mainly because of its size, but I
>> >don't think it was any more arboreal than a cat, probably much less. Like
>> >all other dinosaurs (save a few specialized birds), it couldn't sprawl
>its
>> >legs, for instance. IMHO, birds only became arboreal after they were
>capable
>> >of flying at Pygostylia level. I don't support the cursorial hypothesis,
>> >either; more in my paper :.-( ...
>>
>> Flight evolving neither from the trees or from the ground??
>
>Er... through the water. Sounds like pseudoscience or like the hardly
>supported hypothesis that humans had semiaquatic ancestors, but it is better
>than both. I got the idea from

Yeah, the Oreopithecus theory.  I had a chance to see the type specimen in 
Florence.  It's a nice specimen...but I don't really buy the 
semiaquatic-ancestor theory.

>Klaus Ebel: On the origin of flight in *Archaeopteryx* and in pterosaurs, N.
>Jb. Geol. Paldont. Abh. 202(3), 269 -- 285.
>
>This article has a few weaknesses, but I think I have "debugged" them (e. g.
>I include HP Tom Hopp's hypothesis that wing feathers evolved for brooding),
>and I have included a phylogeny. I'm going to tell you everything once it is
>published... :.-(


>> BTW, I've always regarded the arboreal hypothesis as more plausible.
>Maybe Microraptor will help prove this...although it > likely didn't really
>live in trees.
>
>The arboreal hypothesis has a few big problems. One is the transition from
>parachuter to glider (not actually necessary) and the transition from glider
>to flyer (necessary). Why don't birds have ordinary patagia? Pterosaurs had
>hair (or was it dinofuzz???) and developed patagia instead of wing feathers.

Oh, I didn't say that the arboreal hypothesis doesn't have problems :-)  I 
challenge anybody to find a hypothesis regarding the evolution of avian flight 
that doesn't have any problems.  However, to me, flight evolving from the trees 
down makes more sense ecologically and biologically.  Chiappe et al. (I believe 
it was them) did come out with a paper last year showing mathematical evidence 
that Archaeopteryx could generate enough lift to fly simply by running.  That's 
great, but I still think it would have been much easier for flight to evolve 
from the trees down.  I don't think that the transition from glider to flier 
was that impossible...and I certainly think that it may have been easier, 
biologically, than the transition from runner to flier.  

Anyway, just my thoughts on a subject (avian flight) that I'm not too excited 
or fond about.  Not that I don't find it interesting, but I just see other ares 
of paleontology now that are much more exciting...

Steve


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Steve Brusatte-DINO LAND PALEONTOLOGY
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