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Re: giant birds

<<Actually (this is kind of funny) wolverines share all of those features (except for the long arms) and _do_ climb trees habitaualy. In fact, all of the extant predators that I can think of that bring their arms into play (i.e. weasles and cats) are also fairly good tree climbers. It seems that all those climbing adaptations are serendipitously good as grabbling adaptations, or is it the other way around? Hmmm.>>

Excellent points. (BTW, the wolverine is not as maniraptoran in forelimb structure than the colugo, unless my memory on the matter is incorrect.) Think that the functional interpretations may work just as well either way around in extant predators. However, I doubt that maniraptorans were using their forelimbs habitually for predation. The immobile shoulder joint does not make for a great grappling adaptation and the closest functional equivalent to the maniraptoran wrist in extant tetrapods (besides volant birds) is that of the juvenile _Opisthocomus_.

I agree with George that biophysically the "ground-up" hypothesis is unlikely, and it bothers me that most paleontologists working in the origin of avian flight arena (Padian, Gauthier, Ostrom) are so dogmatic and narrow-minded in their consideration of maniraptorans as strict terrestrial predators. The functional aspects of the maniraptoran forelimb indicate that it is at least *possible* for them to climb, if not habitually in certain forms. We know that the origin of flight had to come from small theropods, so why can't we say that it is just as, if not more, likely to say that could scurry around in the trees like a colugo?

Matt Troutman

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