[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: Microraptor hanqingi, new species from China.



> On the locomotor adaptations of _M. hanqingi_, it's my
> reading of the
> text that Gong et al. are arguing that _Microraptor_ had an
> *obligate*
> sprawling posture.  Gong et al. claim that the
> morphologies of the
> ilium (especially the acetabulum), femur, and ankle joint
> actually
> precluded an erect, parasagittal gait.  So forget the
> cursorial
> hindlimb proportions, the subarctometatarsalian and
> digitigrade pes,
> and the nonexistent-to-feeble opposability of the manus and
> pes -
> according to Gong et al., _Microraptor_ couldn't run
> bipedally on the
> ground even if it wanted to!

In and by itself, this is not necessarily absurd. Both trains of evidence may 
be correct without colliding - any arboreal form that should happen to descend 
from a cursorial-terrestrial form would necessarily evolve through a stage in 
which well-developed cursorial plesiomorphies coexist with crude arboreal 
apomorphies, and the material evidence *could* be interpreted thus in this 
case. For much older taxa, arboreality can be refuted simply due to the lack of 
sufficient amounts of trees, but for _Microraptor_ this is not as easily done 
anymore. The hypermelanism also argues for a hot-and-humid environment and 
possibly life under a closed canopy. So, the time and place are right for an 
experiment in arboreality. But this does *not* mean it was an *arboreal* 
animal, at least if you don't assume natura facit saltus. It would merely be 
slightly better at utilizing arboreal habitat than its ancestors, which is to 
say "slightly better than not at all".

However, that would require to accept the fact that "avoids" (I would write 
"para-avians" but this is too close to Paraves for comfort) all descended from 
small cursorial-terrestrial theropods. There is nothing to suggest that early 
archosaurs evolved towards arboreality, while early reptiles did so vigorously 
and early enough (they started off very, *very* small and used low woody growth 
as it seems) to require an entirely different critter to result by 
_Microraptor_'s time. Something that had the bauplan of a chameleon or _Draco_ 
perhaps. Not sprawling, but positively splayed.

In short, a paravian "early adapter" of tree habitat would show a mix of 
characters similar to that which can be diagnosed (though not with the highest 
reliability) for _Microraptor_. 

Once again, potentially useful insight wasted on the altar of BANDit dogma. Ah 
well.


Regards,

Eike