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Re: Dromornithids and size limits.
In a message dated 4/12/04 11:34:16 PM Eastern Daylight Time,
<< Birds are tetrapods, as a tetrapod is not defined by having four
TERRESTRIAL limbs. >>
Jaime, I think Eric meant to use "quadruped" here, vice "tetrapod" since I
don't think he was talking about it in the taxonomic sense. I'm guessing most
us know that birds are tetrapods too, except literally (i.e., "four-footed").
As I understand it, his argument is that birds have gone too far down an
evolutionary path, with forelimbs that are probably too specialized to
into potentially-manipulative appendages (in the case of the Moa, the wing had
disappeared completely, bone and all). Perhaps the same can be said of some
mammals (e.g., cetaceans, sirenians), but I suspect even bats retain enough of
the forelimb structure that they could, given the right conditions, evolve
hands out of their wings.