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Re: origin of bats/reply 2 to TMK




On Jun 20, 2008, at 2:07 PM, Mike Habib wrote:

So the question is, if bats were climbing using all fours, why and how would the change to using only the thumbs and folding the other fingers under actually work? IMHO there has to be an intermediate stage because if something is working right (climbing hands) they don’t change without intervention.

This is an assertion, not really a robust conclusion.

No this is a question followed by red flag because a leap of logic has appeared in traditional thinking.


There is not reason to think that climbing hands can't evolve dual function under specific selective regimes.

Dual function? Name an analogous situation.

The fact that we can't imagine a particular story to go with it is of limited importance in this regard. Mechanically, climbing with only digit one, while folding the other digits clearly works (as bats currently use this method).

But this is clearly secondary. Evolution always chooses the best solution to a problem. Try climbing with only your thumbs or ask a cat to do so and you'll see that's not the best solution.


To determine how a standard climbing hand gets to that point, we need more fossil evidence and phylogenetic analysis.

True. We don't know the transition. But at the transition, bats were at liberty to do something else with their hands.


Just assuming that there has to be a bipedal stage is not recommendable.

Except that we have two examples of bipedal vertebrates that grew wings. And bats are inverted bipeds. That's irrefutable. And their outgroups were experimenting with holding prey in their forepaws. There's your dual function.


Hey, I'm just the messenger. It's just a new idea. That's all.

David





Cheers,

--Mike


Michael Habib, M.S. PhD. Candidate Center for Functional Anatomy and Evolution Johns Hopkins School of Medicine 1830 E. Monument Street Baltimore, MD 21205 (443) 280-0181 habib@jhmi.edu



David Peters davidpeters@att.net