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RE: Microraptor also ate fish



Tim Williams wrote-

> > Saying Microraptor lacks *any* arboreal traits is clearly hyperbole.
>
> Not at all. As I've said, I'm using the strict definition of
> arboreal: rarely spends time on the ground, and forages and shelters
> in trees. Simply entering a tree does not qualify as arboreal.

But as I argued, by limiting "arboreal trait" to "traits only found in taxa 
which are arboreal and can't serve another purpose", you're probably going to 
be blind to many arboreal taxa.  If the latter percentage is high enough (e.g. 
a third of arboreal taxa don't have such strictly arboreal traits), then saying 
Microraptor lacks such strictly arboreal traits isn't going to tell us much 
about its actual habits.  We need to know that percentage before we can say 
anything substantive.

> > The blue whale might lack any arboreal traits. Microraptor has a lot. It 
> > could clearly climb
> > trees if it wanted, was small, had prehensile hands and feet, sharp 
> > recurved unguals,
> > elongate limbs, a tail that could swivel at its base and was relatively 
> > swift, feathers to
> > cushion a fall, a distally placed hallux, traits to increase aerial motion 
> > (incipient alula,
> > asymmetrical feathers) which could only be achieved by using an elevated 
> > perch, etc..
>
> None of these attributes are (strictly speaking) arboreal characters.
> They are aerodynamic and/or raptorial characters. Perhaps some of
> these could have been scansorial behaviors as well (and therefore
> employed for tree-climbing). Unfortunately, I think the term
> "arboreal" is often used far too permissively, such as for behaviors
> that are associated with climbing or launching from elevated
> vegetation.

But we still don't know how "strictly arboreal characters" are distributed in 
arboreal taxa.

> BTW, I'm not sure what you mean by _Microraptor_ having a "prehensile"
> manus. I had thought _Microraptor_ was incapable of holding any
> object with only one hand. I also think calling the foot "prehensile"
> is bit of a stretch - although at least here (unlike the hand) the
> is evidence for digital opposability.

I meant the fingers and toes could curl inward to hook narrow objects.  This is 
a trait which would be useful to an arboreal taxon, while our example the blue 
whale lacks this ability, one aspect of it being very poorly built for an 
arboreal lifestyle.

> > Now, some of these could work for predation, scansoriality, cursoriality, 
> > etc..
>
> Especially if that's what they are adapted for.
>
> > But my point was that we can't just discount these because they could work 
> > or did work for
> > another purpose.
>
> Yes, I agree. That's were exaptation comes in. But this alone does
> not mean that such characters were arboreal.

But it doesn't mean they're not used for an arboreal lifestyle either, which 
seems to be your default.

> > How many arboreal taxa today also use their tree-climbing features for 
> > other purposes?
> > Probably a lot.
>
> But these are arboreal taxa. We haven't even established that
> _Microraptor_ was arboreal.

And because many species today probably use the features that enable their 
arboreal lifestyle for other purposes, we can't establish that Microraptor 
wasn't atboreal just because its features could or were used for additional 
purposes such as predation.

> > How many are hindered by features like Microraptor's parasagittal hindlimb 
> > motion?
> > Probably a lot.
>
> Name one. :-)

Birds only have two grasping appendages (except hoatzins; three if you count 
parrots).
Monkeys lack an aerodynamic surface, so will be injured or killed more often if 
they fall.
Sloths lack a safe way to travel between trees.
Examples are plentiful because organisms only have to be just good enough at 
what they do to survive to mate with low enough mortality to maintain a 
population.  So just saying this feature or this set of features isn't ideal 
for an arboreal taxon isn't sufficient to discount arboreality.

Basically, your position that "unless Microraptor has traits only found in taxa 
which are arboreal and can't serve another purpose, and since it has traits 
which could hi
sn't been demonstrated to be true in extant animals to my knowledge.  Until we 
have some knowledge of how traits are distributed in living animals compared to 
their lifestyles, it's just an assertion, one that seems implausible to me.

Mickey Mortimer