Re: Dinosaurs and birds

[Tim Williams <twilliams_alpha@hotmail.com>]

Mike Keesey wrote:

> _Archaeopteryx_ is probably not ancestral to modern birds, but it's 
> probably fairly similar to some actual ancestor in many ways. In most ways 
> it's a good ancestor model.

Yes, most models that provide a hypothetical pathway for the evolution of 
avian flight use _Archaeopteryx_ as the prototype for how later birds came 
to fly.  There's no phylogenetic or ecomorphological evidence to overturn 
that assumption, AFAIK.

> Yes, but (last I heard) he also calls any arboreal, volant dinosauromorph a 
> "bird", and his argument is almost more ecological than phylogenetic. I.e., 
> he doesn't disagree radically with "normal" phylogenies (well, maybe in a 
> few areas, but that's not entirely relevant to the basic idea), but he 
> thinks the lineage leading to modern birds was arboreal and volant for a 
> long time before _Archaeopteryx_, and that most Mesozoic dinosaurs we know 
> are secondarily terrestrial and nonvolant (as well as a few Cenozoic ones 
> of course!).

This leads me to ask, are there any arboreal, volant dinosauromorphs aside 
from birds?  Microraptorans, while not avians, are darn close to birds; they 
were probably arboreal, and maybe volant (biplane-style).  I'd be willing to 
bet that basal oviraptorosaurs were arboreal too.  But that's about it.  I 
have trouble believing that the first sauropods lived in trees, or even the 
first tyrannosaurs.  Then again, as Mike Taylor says, "I have a hard time 
believing" is not admissable evidence.  :-)

I've heard that Mr Olshevsky is self-publishing a book (or books) about 
"BCF".  Then again, I've been hearing this for quite a while now.

> This argument hasn't found a lot of support, although some think flight may 
> have originated somewhere in basal _Maniraptora_, at least.

Yep, that's the gist of Greg Paul's idea, as per PDW and DA.  "BCF" is far, 
far more radical, and has far, far less support.

> (Then again, some don't even think _Archaeopteryx_ was volant.)

Is the non-flying _Archaeopteryx_ idea still around?

Cheers

Tim

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