Re: Back-evolution of limbs.

[Ronald Orenstein <ornstn@inforamp.net>]

At 11:08 AM 28/06/98 -0700, you wrote:
>I would like to insert a question here........ was the original limb composed
>of five digits
>before going onshore , or developed after becoming terrestrial ?
>Earl Wood

My understanding is that the earliest known tetrapods had even more than five
digits per limb, but I believe that these creatures (which are basically
lobe-finned fishes with legs, though in a way so are we of course) may well
have been pretty much water-bound.  I am not sure at what stage their
descendants became terrestrial (though to be truly terrestrial they would have
had to modify not just their bodies but their breeding mechanisms, either
through the development of the amniotic egg or some of the strategies used by
land-dwelling frogs (eg live birth, mouthbreeding etc)).  Even the five-toed
Ichthyostega was. I believe, at least partially aquatic according to most
books.
--
Ronald I. Orenstein                           Phone: (905) 820-7886
International Wildlife Coalition              Fax/Modem: (905) 569-0116
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Mississauga, Ontario, Canada L5L 3W2          mailto:ornstn@inforamp.net