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Christiansen and Bonde, 2002 (was Re: Feduccia Reviews Paul's DOTA, Comments)



Mickey Mortimer wrote:

Actually, a paper was written for the exact purpose of refutting Jones et al.'s arguments-
Christiansen and Bonde, 2002. Limb proportions and avian terrestrial locomotion. J. Ornithol., 143, pg. 356-371. Not without its problems, but a good study nonetheless.

I was very impressed by the paper. Centre of mass (CM) calculations are always a little "warm and fuzzy" when it comes to fossil taxa. They involve a LOT of assumptions - lung volume and extent of pneumaticization; width at the chest and hips, etc.


However, IMHO the most sigificant finding of Christiansen and Bonde (2002)'s study is that the femur of _Caudipteryx_ appears to no show thickening of the diaphysis associated with avian locomotion patterns (contra Jones et al.). Modern birds have proportionally shorter and thicker femora, because of their derived hindlimb kinematics (rotation occurring about the knee rather than the hip, which puts greater stress on the femur, which is oriented subhorizontally during non-rapid terrestrial locomotion). The circumference of the femur in _Caudipteryx_ is significantly less than that of ground birds, and similar to other non-avian theropods. I think this result deals a lethal blow to the idea that _Caudipteryx_ was a "Mesozoic kiwi" that had an avian-style posture. _Caudipteryx_ was a long-legged, short-tailed non-avian theropod.




Tim

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