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Re: Resolving the Digit Loss Debate?
In a message dated 6/8/01 2:23:48 AM EST, firstname.lastname@example.org writes:
<< George proposes that the wing was selected for early in dinosaur
evolution, and that this is what drove manal digit reduction.
This can be tested in examining the limbs of basal dinosaurs and
their closest outgroups. >>
You must remember that the earliest dinosaur wings retained the plesiomorphic
grasping function and did so at least to the common ancestor of the
ceratosaurians. The flying function evolved gradually and incrementally on
top of the already present grasping function, so the earliest wings would not
have anatomically resembled the highly modified forelimbs that birds possess
today and certainly would not have functioned like them. There are no
forelimbs like these in extant animals that I know of; it is perhaps our job
to reconstruct what these forelimbs were like from the fossil record of early
theropod descendants of these dinobirds.