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Re: Microraptor preyed on birds (official paper in PNAS)



 (1) The pes shows modifications that have been associated with
 scansorial or even arboreal behavior (e.g., Xu et al., 2000). These
 modifications include the elongation of the penultimate phalanges
 and the more distal position of the hallux.

These modifications are so weak that I wonder if they have to do with grasping prey (think secretarybird) and/or the small size of the animal.

 (2) The feathers of _Microraptor_ are elaborately modified for
 aerial locomotion - and arguably only suitable for descents from high
 places.

So far, so good...

 Admittedly, in terms of scansorial/arboreal adaptations, the pedal
 modifications are hardly compelling. The quantitative and
 qualitative analyses of Dececchi and Larsson (2011) explicitly
 rejected arboreality in _Microraptor_ (and archaeopterygids too).
 This study focused on the lack of branch-grasping adaptations and
 limited limb joint mobility in _Microraptor_, which makes it
 extremely unlikely that this theropod could move about within the
 tree-crown, or descend tree trunks. However, the sort of
 trunk-scaling envisioned by O'Connor &c (Fig. 3) does not entail
 branch-grasping.

I'll have to try to find out if the hindlimbs are much too long for trunk-climbing. The lower legs in particular are unusually _long_, not short as expected in an animal that has parasagittal legs and needs to hold its center of gravity as close to the tree trunk as possible.

 I've often wondered if the aerodynamic plumage of _Microraptor_,
 _Archaeopteryx_ , _Anchiornis_ etc was to compensate for the
 extremely rudimentary scansorial/arboreal abilities.

Then wouldn't we expect parachuters instead of gliders? *Microraptor* with its long, narrow wings looks like a glider. *Archaeopteryx* with the fairly wide gaps between its short, broad, round wings and its body looks like nothing at all.