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Re: 11th specimen of Archaeopteryx



On Wed, Nov 2, 2011 at 1:14 AM, Don Ohmes <d_ohmes@yahoo.com> wrote:
> On 11/2/2011 1:49 AM, Scott Hartman wrote:
>
> Your implied thesis is that Archie and similar animals were physically
> incapable of climbing, and so could not roost.

My explicit thesis is that Archie shows no adaptations at all for
climbing, and does exhibit adaptations for other activities.  As such
it's simply not responsible to continue to use Archie as the
inflection point for all of these hypothetical scenarios (or, if we
are to use Archie, to come up with scenarios that are reflected in its
anatomy).

> I think you should take a closer look -- specifically at the morphology of
> the trees dominant at the time, and the many animals that can and do climb
> -- even w/out claws, which Archie-types had both fore and aft.

I've spent quite a bit of time looking at this.  Also I've spent more
than my fair share of time looking at Archaeopteryx specimens.  Not
that it makes me right, but there's nothing in my time spent examining
the issue that makes me inherently wrong either.

> Perhaps old Arch did not want to climb, or maybe he even lived on an island
> w/ no trees -- but he certainly had sufficient tools to accomplish the task.

I have the tools as well.  And honestly, if you looked at humans
totally outside of the context of other primates, you could make an
even better argument that we foraged on the ground but roosted in
trees (in our case this actually was true of some of our ancestors).
But once you put it into a phylogenetic context it becomes clear that
the phylogenetic trend is towards reducing those adaptations for
climbing.  So even though tree houses and jungle gyms are popular
human pastimes, it would be clear from a phylogenetic analysis that
humans are reducing our ability to climb trees, which would be an
honest perspective on our evolutionary "priorities".

Likewise, if you map out paravian phylogeny and and where traits
associated with arboreality show up, you'd see that there's simply
nothing at all that shows up with Archie.  It's not that physics
prevents any Archie from ever having gone up a tree, it's that there's
simply no phyletic trend towards such activity at that point.  Later
in the Early Cretaceous you actually do see those traits show up,
although often in a mosaic pattern of acquisition.  It's that trend
that I think is compelling, not debating whether any given animal
could "possibly" accomplish something, but rather, what does the
phylogenetic trend actually suggest was going on?

Ok, I'm off to catch some Z's before heading to Las Vegas.  Have fun guys!

-Scott


-- 
Scott Hartman
Scientific Advisor/Technical Illustrator
(307) 921-9750
website: www.skeletaldrawing.com
blog: http://skeletaldrawing.blogspot.com/