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Re: 11th specimen of Archaeopteryx



On Oct 27, 2011, at 10:53 PM, Tim Williams wrote:

> Scenario building is more than just fun - I also think it's
> scientifically valid to rule in or out certain lifestyles.  Observed
> changes in morphology can be associated with inferred changes in
> ecology.

In a general sense, absolutely.  So, for example, there are some very good 
studies that use statistically robust methods to develop "ecotypes" and 
correlate them with morphology.  But very specific scenarios, such as "X animal 
used Y structure in this precise way, which allowed for the evolution of Z" 
tend to be real long shots, at least most of the time.

> I can appreciate that long, asymmetrical feathers along the forelimbs
> could be useful as control surfaces in terrestrial-based locomotion.
> However, the purpose of such feathers along the tail, and (especially)
> the metatarsus seems hard to reconcile with terrestrial-based
> locomotion.  Xu et al. (2003) even used the presence of long
> metatarsal feathers in _Microraptor gui_ to refute a "ground-up
> hypothesis" (their words), because they would be a hindrance to
> cursoriality.  Although I think this is an exaggeration, the fact
> remains that small feathered paravians (including microraptorines,
> archaeopterygids, and confuciusornithids) were not exactly built for
> speed on the ground.  I'm aware that control is more about
> maneuverability than velocity.  But on that score it is difficult to
> accord the hindwings and long feathered tail with increased agility on
> the ground.

I tend to agree, and I'm not actually arguing that Microraptorines were 
terrestrial, per se.  However, agility in a terrestrial setting can be more 
than simply running.  The key issue in either ecological model is the focus on 
control.  I have a lot of thoughts on this issue (as do my honorable 
co-authors), actually, but I'm going to make everyone WFTP.  

Cheers,

--Mike H.


Michael Habib
Assistant Professor of Biology
Chatham University
Woodland Road, Pittsburgh PA  15232
Buhl Hall, Room 226A
mhabib@chatham.edu
(443) 280-0181