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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
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
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.