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RE: JFC-Bloodiest Battle ??




Dan Chure wrote:


> I have not seen the Longrich and Currie paper, so I am speaking from a
> bit of ignorance here, but that has not stopped me before. Forelimb
> analysis can provide insight into strength, planes of movement, etc.
> Its a further step to what those movements were used for by the
> organism. When confronted with something as bizarre as alvaresaurids
> and the desire to make sense of them, getting them to fit into a known
> niche, such as myrmecophagy, can be satisfying. And it may even be
> correct. I would maintain that we should be circumspect because the
> world of the past may have offered opportunities different and more
> diverse than the present. I guess I don't see a problem with saying
> these are damn weird beasts and we have no real understanding of what
> the hell they were doing.


Yep, I agree wholeheartedly.  I think there has sometimes been a temptation to 
'shoehorn' fossil taxa into modern analogs.  The forelimb morphology of 
alvarezsaurs is consistent with digging up insect nests.  However, to suggest 
that this group filled a niche similar to modern myrmeocophagous mammals 
(anteaters, pangolin, aardvark, etc) depends on how far one is willing to 
stretch the definition of "niche".


> To return to a long abandoned thread, when the flight analysis of
> Microraptor showed that the feather arrangement as preserved did not
> give the expected gliding path, re-examination of the feathers yielded
> an arrangement that did give the expected path and was viewed as
> success. Maybe the new arrangement was correct, or maybe it just
> satisfied expectations. Maybe a much more vertical drop WAS the hunting
> strategy of Microraptor and not too relevant to the origin of flight.
> Or maybe gliding developed from such a death from above hunting technique.


The pre-_Archaeopteryx_ stage of avian flight does appear to be a vacuum, so 
feathery critters like _Microraptor_ are often used to fill it.  Not in a 
chronological sense, but in an ecomorphological sense.  _Caudipteryx_ has also 
been recruited to fill the same role, under the 'Pouncing Proavis' model (which 
posits that drag, rather than lift, was the primordial aerodynamic force in the 
origin of avian flight).  As for _Microraptor_, its form of aerial locomotion 
(whatever it was) may have indeed been a 'dead end' in terms of powered flight, 
and not be primitive for the Eumaniraptora clade.  


> My arms are tired from waving, so I shall retreat until a future time.


A bit of arm-waving never hurt anyone.   Just look at the evolution of birds!   
;-)


Cheers

Tim
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