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Re: Saurischia and Ornithischia pelvis
Being able to rest on it seems to be as much a question of the right
orientation of the bone as it is of having the right surface, because
the loaded bone should be approximately under the center of mass.
Of course having generally more gracile pubes without the massive distal
expansion doesn’t help, but both the right positioning and the right
shape and robusticity are required if the bone is supposed to be used
An ornithischian with an opistopubic condition wouldn’t be able to
effectively use its pubis to support its weight while resting, even if
it had a pubic boot. The longer part of the bone is sticking out
caudally, there’s no way it could get it under the center of mass unless
it was sitting on it near-vertically (and caudal flexibility probably
wouldn’t have allowed even that).
I don’t know how important an ability this was for saurischians (though
that they readily lost it to adapt for herbivory suggests it wasn’t very
important), but if it was used the way that was suggested, the
plesiomorphic orientation of the pubis would help fulfill an actual
function in at least some saurischians, as opposed to being totally useless.
On 13.07.2015 23:05, tholtz wrote:
And I think people are conflating the actual question (orientation) with
the not-related issue of a pubic boot (a distal expansion of the pubis,
regardless of the orientation). The original poster asked about the
position of the pubis.