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Re: Sinocalliopteryx (Theropoda: Compsognathidae) ate confuciusornithids and dromaeosaurids

Thomas R. Holtz, Jr. <tholtz@umd.edu> wrote:

> On top of all this, I think there is an unconscious assumption in a lot of
> discussions that the flight states are "stuck on the ground like a turtle"
> vs. "as aerial as a sparrow or starling".

And on top of all that, the arboreal / cursorial debate often boils
down to this same kind of dichotomy: the ancestors of birds either
spent all of their time on the ground, or all of their time in trees.
No in-between.  This seems very silly.

>From a biophysical perspective, how much different is (1) a
_Deinonychus_ clambering up a 2-tonne tenontosaur using all four limbs
and (2) a _Microraptor_ clambering up a tree trunk using all four
limbs?  The second would actually be easier, because the substratum
isn't fighting back.