Re: Microraptor also ate fish

[David Marjanovic <david.marjanovic@gmx.at>]

Maybe what should be researched first is whether *M.* was capable of 
powered flight and whether it was capable of gliding. (And the same, 
actually, holds all the way to *Confuciusornis*.)

If it was capable of powered flight, it didn't need trees to take off. 
It used to be thought that the ability to take off from the ground is 
special and must have been the last step in the evolution of flight -- 
but, as Mike Habib just reminded us, it's not special at all: all extant 
birds capable of powered flight take off by jumping, no matter from 
where -- even hummingbirds derive 80 % of the necessary energy that way. 
No bird just stands there and flaps till it takes off.

At the same time, if it was capable of powered flight, it could have 
been able to spend a lot of time in trees _anyway_, _without_ being able 
to climb up a tree! Very few birds today are able to start at the ground 
and climb up a tree trunk, and, AFAIK, all of them have very special 
adaptations to this. Even juvenile hoatzins, with their finger claws, 
have strong perching feet and additionally use the beak, options denied 
to *Microraptor* or *Archaeopteryx*. Most arboreal birds are able to 
perch in a tree but more or less unable to climb.

If it was instead a glider, it _must_ have used some elevated perch 
(pretty obviously a tree given the landscape it lived in), and it _must_ 
have been able to climb there from the ground.

If neither of these worked, and all those asymmetric feathers had 
_another_ purpose _instead_ (display, brooding, quick turns during 
running, whatever), then it doesn't need to have had any climbing 
abilities (beyond those required simply by its size) and could have been 
exclusively terrestrial.

So: obligatory glider or not?

(I leave off parachuting, because the shape of *Microraptor* doesn't 
look like what I'd expect of a parachutist. But it would have the same 
requirements as gliding: elevated perch and ability to get there by 
climbing.)

> There are many different types  of grasping feet. The feet of many
> ornithurans and enantiornitheans are adapted for anisodactyl
> perching. The grasping feet of fruit bats are adapted for suspending
> from thick tree branches. The grasping feet of dromaeosaurs are
> different to both (though more similar to birds than to bats).

More specifically, the Fowler et al. (2011) paper shows that 
*Deinonychus* could have grasped a branch -- but only at one specific, 
very weird angle, far away from 90° to the long axis of the body.

> There may indeed be individual  points of similarity between the two,
> and from that standpoint you could argue that the foot of
> _Microraptor_ could be used for roosting or perching. But I'd like to
> see that particular notion framed as an explicit hypothesis that can
> be tested. In a previous post you mentioned reconstructing the pes of
> _Microraptor_ using the musculoskeletal anatomy of modern birds as a
> template, to investigate if the foot of _Microraptor_ was
> biomechanically capable of grasping a branch. I think this is a great
> idea.

I agree.