Re: Back-evolution of limbs.

[Jeff Hecht <jhecht@world.std.com>]

John Bois wrote:
>
>Why is it that birds--and only flying birds at that--are the only
>creatures to return to their former mode of locomotion, i.e., they may
>become secondarily flightless.
>
>I haven't heard of a bat or flying squirrel doing such a thing.
>
>And I don't know of any swimming mammal or bird which has returned to a
>terrestrial existence...

But marine mammals and reptiles _have_ returned to their ancestral medium,
the sea, and the flippers of an ichthyosaur or dolfin resemble the fins of
fast predatory fish, e.g. sharks.

That said, you do raise an interesting question. Do any living birds use
their wings for anything other than flight (or swimming)?
- Jeff Hecht

Jeff Hecht     Boston Correspondent    New Scientist magazine
525 Auburn St.,          Auburndale, MA 02466             USA
*****NOTE NEW ZIP CODE -02466- AS OF JULY 1, 1998******
tel 617-965-3834 fax 617-332-4760 e-mail jhecht@world.std.com
URL: http://www.sff.net/people/Jeff.Hecht/
see New Scientist on the Web: http://www.newscientist.com/