Re: Crowley Hot-Shot... was Re: tree-climbing hominid

David Froehlich (
Thu, 12 Oct 1995 16:05:55 -0500

> "Paul Crowley" writes:
> Pa> The extent of this change is grossly under-appreciated by nearly
> Pa> everyone - but especially by the non-AAT'ers. (David Froehlich in
> Pa> this thread is one example.) It's like changing car into a boat,
> Pa> re-locating the engine to the back to provide power. It can be
> Pa> done; but you have to do it in 50,000 steps; each stage has to be a
> Pa> fully working model and EACH step has to have benefits to the user
> Pa> making the car/boat significantly more effective than it was in the
> Pa> previous stage.

Just thought of a perfect example of where the engine moved from the
front to the back. Are you familiar with the anatomy of a turtle? It
has a shell composed of dermal ossifications fused to the ribs. The
interesting thing here is that the scapula and entire shoulder girdle and
limbs are on the inside of the ribs. How did this happen? Did you have
a turtle ancestor who could not move his entire forelimb while the
scapula was moving inside the ribs? Of course not, but they still have
this morphology. How could it have occured? Gradually? No. You can
actually demonstrate (I think Reiner Zangerel did it) that it was a
developmental change and that it could have occured suddenly. The
shoulder girdle (an the pelvic girdle) form very early in the development
of the organism and the ribs are delayed (forming from front to back).
By the time the ribs get to the girdles, they are already formed and inside.

I don't know if this helps the arguement along any, but it does provide
an example of moving the engine from the front to the back in your analogy.

David J. Froehlich Phone: 512-471-6088
Vertebrate Paleontology Laboratory Fax: 512-471-5973
J.J. Pickle Research Campus
The University of Texas, Austin, Texas 78712