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Re: Campbell's even crazier than a MANIAC? (archeopteryx climbing)



First, David, I saw the figure in the paper and do not catch what do you say
restricts femoral abduction in Microraptor. Not anything different from what
should impede abduction in the pigeon.

Well, it's just mechanically impossible given the femoral head and the acetabulum. The ilia are broken lengthwise to make the preserved position possible.


Second, Jaime, you are right in that Cracraft 71' never said the femora can
splay out laterally in the horizontal plane. But they can rather abduct much
once they retracted so that the facies articularis antitrochanterica is no
longer in contact with the antitrochanter. So, yes, you should not have
completely-splayed out hindlimbs, but each hindlimb may have formed a, say,
90° angle or somewhat more (not know of quantities) with the other in
anterior view. Not the best for gliding but best than strictly parasagittal
limbs.

Fine, but pigeons have a distinct femoral neck and a somewhat rounded femoral head, right? *Microraptor* lacks all of that. (And so does *Archaeopteryx*.)


Third, as far as I know, *Archaeopteryx* is more basal within the Avialae
than *Microraptor* is within Deinonychosauria.

That doesn't mean anything except as a statement about the completeness of the fossil record.