Re: New Mesozoic bird papers (advance publication)

[Tim Williams <tijawi@gmail.com>]

Denver Fowler <df9465@yahoo.co.uk> wrote:

> I couldn't agree more. Feduccia's (1993) measurement method is flawed: and was
> pointed out as such by Glen and Bennett (2007) -which isn't cited at all.


Yep, the omission of Glen and Bennett (2007) is bewildering to say the
least.  G&B's claw study provided quantitative data in support of the
hypothesis that the first birds (and their maniraptoran relatives)
spent time in *both* the trees and on the ground.  This is something
that a lot of us had suspected, and it delivers a kick in the cojones
to the old "arboreal-versus-cursorial" dichotomy.


However, the Burnham &c paper seems to want to put _Archaeopteryx_ and
_Microraptor_ permanently in the trees as "specialized arborealists".
This does not gel with the osteologies of these animals, which point
to a bare minimum of adaptations for aboreal locomotion.  To me, these
maniraptorans look like terrestrial cursors upon which a relatively
few arboreal and aerial adaptations had been grafted - such as the
shape of the claws, and the development of long aerodynamic feathers
on the limbs and tail.


It is also inappropriate to invoke the claw curvature of
_Archaeopteryx_ and _Microraptor_ in support of perching, because
(unlike perching birds) _Archaeopteryx_ and _Microraptor_ did not have
a specialized perching pes.  Although the hallux was positioned
further down on the pes compared to the primitive theropod condition,
it was still very short compared to modern perchers, and was not even
reversed.  I'm ready to accept that these maniraptorans did climb
trees; but the notion that _Archaeopteryx_, _Microraptor_ and friends
were "specialized" for arboreality is absurd.  They were probably
experimenting with arboreal (and aerial) locomotion, but IMHO were not
specialized for arboreality, or for flight.



Cheers

Tim