Re: Dissecting the Aquatic Ape: Bipedalism
Elaine Morgan (elaine@desco.demon.co.uk)
Mon, 15 Jul 1996 21:50:34 GMT
In article <Du6ACE.9B1@inter.NL.net> ghanenbu@inter.nl.net wrote...
tal features associated with knuckle-walking are:
>
> -dorsally extended articular surface of the head of the metacarpals
> associated with hyperextension of the metacarpophalangeal joint.
> -a transverse bony ridge on the dorsum of the metacarpals to prevent
> the joint from collapsing under the weight of the body.
> -widest diameter of the metacarpal heads located dorsally.
> -proximal phalanges short relative to length of the metacarpals in
> relation to humans and orang-utans.
> And further:
> -distal articular surface of the radius deeply concave.
> -bony ridges on scaphoid and dorsal distal radius stabilizing the
> wrist joint.
This is a very useful list. Can you settle the query of whether
or not gorillas and/or chimps can flatten the palm and exxtend the
elbow at the same time? I have seen it posotivelt stated that
they cannot.
>
> None of the above features are found in fossil hominids.
> Shouldn't we concentrate on these fossilizable characters when it
> comes to assessing locomotor behaviour of extinct ancestors..?
Yes
n the basis of the above mentioned skeletal features associated with
> knuckle-walking we can at least make the testable prediction that if
> the LCA was a knuckle-walker,fossils of it will show these features.
>
And if it was that would make a bit of a mess of the cladistics,
wouldn't it?
Elaine
|