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Re: giant birds




<<I'm not sure any tree would ever require a "miracle," but the kinds of changes George proposes are still not optimal on any tree currently
accepted by the community. The simplest set of transformations on any of them would resemble the ground-up hypothesis; I know not everyone buys it, but it's simplest. The trees-down hypothesis is less simple, and BCF less simple than that. DOes that mean they're "falsified?" No - only that the best-supported trees we currently have prefer a different model.>>


I agree with that George's hypothesis requires a good deal more transformations (and not to mention missing fossils) than the ground-up hypothesis, but I disagree that the ground-up hypothesis is simplier than the trees-down hypothesis. For some reason, everybody follows Ostrom's (1974, 1979) interpretations of certain features shared by theropods and birds as being primarily predatory adaptations. An equally good, if not better, case can be made for tree-climbing adaptation. If anyone denies the similarity of the maniraptoran forelimb compared to the _Cynocephalus_ (an obvious climber and glider) forelimb and argues for a closer similarity to the forelimb of a wolverine (a predator that actively uses its forelimbs) I'll seriously wonder about somebody's mental health. Think about it: long, strong forelimbs, flexible wrist, long fingers and strongly recurved claws. Maniraptorans sound like at least potential climbers.

Matt Troutman
m_troutman@hotmail.com

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