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Re: bauplan convergence

In a message dated 6/8/00 9:53:49 AM EST, ornstn@home.com writes:

<< If you are talking about birds, then it is perhaps relevant that birds 
could not "re-evolve" such a form because, strictly speaking, the theropod 
lineage never evolved it in the first place - are they not primitively 
bipedal within dinosaurs? >>

I don't think dinosaurs were primitively bipedal, but they probably were 
primitively scansorial. It is fairly straightforward to evolve a quadrupedal 
form (e.g., sauropods) as well as a strictly bipedal form (e.g., theropods) 
from a scansorial form, much more difficult to evolve a quadrupedal form from 
a strictly bipedal form.