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Re: Ceratopsians: sprawling or straight?
At 03:15 PM 12/27/97 -0500, tons wrote:
>I've never studied ceratopsian bones so I only have questions. Why
>would most dinosaurs have their limbs and feet in linear fashion
>under their hips or shoulder girdles and ceratopsians not?
Ancestrally, dinosaurs were bipedal. The *hind* legs, being used in
locomotion, were under the hips. The arms were less constrained, being
used for grasping. This means that the conformation of the front legs in
*any* group of quadrupedal dinosaurs has evolved separately (there were at
*least* three distinct origins of quadrupedality in dinosaurs, four if you
count hadrosaurs as quadrupedal).
Thus, ceratopsians would be different because they arrived at
quadrupedality in a different manner than other dinosaurs. (Note, i am not
saying I agree with this conclusion, only that there is no evolutionary
problem with it).
>Would an animal that large be able to move quickly with an
>articulation at the knee (or otherwise) that was not linear?
This is not clear, It depends on *how* it departed from linearity.
May the peace of God be with you. firstname.lastname@example.org