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Re: Campbell's even crazier than a MANIAC? (archeopteryx climbing)



> >>>That for sure proves that *if* Archie had any
> sort of climbing 
> ability, it did
> not climb the same way as e.g. a gliding squirrel or a
> _Draco_. But the
> "theropods couldn't" argument still needs to
> explain how something like
> _Microraptor_ evolved in the first place and by all
> accounts was quite
> successful.<<<
> 
> It seems to me that puts the theoretical cart before the
> empirical 
> horse.  If theropods as a group (including Microraptor)
> lack evidence 
> of specialization to engage in the bahaviors that have been
> 
> hypothesized for Microraptor then it is up to us to come up
> with better 
> (non-falsififed) hypotheses; it is _not_ the job of the
> morphology to 
> conform to preconceived notions on how flight "should
> have" evolved (or 
> when it evolved).

True, if I would argue for arboreality of _Microraptor_. But what I'd argue for 
here is that it undeniably differs from most relatives in the same size class 
in an adaptation (hindlimb wings) that is detrimental to the way smnall 
theropods escaped predation - running away. The leg feathers were unlikely to 
be helpful as long as the toes touched the ground, and probably were even quite 
detrimental in any sort of vegetated habitat. Especially as they were not leg 
but midfoot feathers.

So there must have been *something*, either in its ecosystem or in its 
behavior, that allowed these features to evolve in the first place - lack of 
predators, de-emphasis of cursoriality, whatever. 

As with Archie, _Microraptor_ was not a percher. This is certain. Apart from 
that, it was almost certainly less able to run away from predators than, say, 
_Sinosauropteryx_. Whether this difference was prominent enough to matter is 
arguable, but if it was, it needs to be explained. And I think that it is hard 
to challenge the assumption that Archie, _Microraptor_, as well as all other 
"protobirds" were terrestrial bipeds first and foremost. But were they anything 
else, and if yes what, and to what extent?

(Think Picini - these woodpeckers have among them several genera which are more 
terrestrial, namely _Picus_ but it can be best seen in the 
_Colaptes_/_Chrysoptilus_ subgeneric division of the flickers. All Picini are 
very typical woodpeckers, but the adaptations to a *more* terrestrial lifestyle 
can still be seen if one looks closely enough. Similarly, the hindlimb wings of 
_Microraptor_ can be seen as as adaptations to a *less* terrestrial - but still 
*mainly* terrestrial - lifestyle, but unfortunately we have no 
_Colaptes_/_Chrysoptilus_ situation here that allows direct comparisons between 
extremely close relatives. Perhaps _Graciliraptor_ or "Dave" could afford a 
comparison.)

Augusto's point is interesting. If I understand it correctly, it is basically 
the same purpose Chatterjee ascribes to _Microraptor_'s hindlimb feathers once 
airborne, but of course using the arms for such a purpose a) is easier and b) 
works while still on the ground. Rheas, whose wings are quite long by ratite 
standards, often employ their wings in terrestrial maneuvring; it might be 
worthwhile to compare the shoulder region of rheas and cassowaries, and see if 
analogous differences are found between winged and non-winged small 
maniraptorans.


Regards,

Eike

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