Re: Bidpedalism

Gerrit Hanenburg (
Sun, 4 Jun 1995 14:08:00 GMT

In article <3qki2g$> (HARRY R. ERWIN) writes:

>I ran into an interesting book by Oxnard on the postcranial adaptions of
>primates and australopithecines. The evidence is fairly strong that their
>motor behavior was like nothing known today. You can deduce that they
>probably were bipedal on the ground, but spent most of their time moving
>arboreally in the trees. H. habilis seems to be similar.

I didn't read Oxnards book and maybe my comment is premature, but how
much can we deduce from anatomy alone?
The hindlimb of AL 288(Lucy) was short both absolutely and relative to
forelimb and trunk lengths;this would have affected stride length and
walking velocity.
The hindlimb joint sizes are bigger than those of apes but much smaller
than modern humans even when differences in overall body size are taken
into account;this suggests less complete adaptation to full weight
bearing by the hindlimb.
Locomotor reconstructions based on the Laetoli footprints suggest a
relatively short,but not necessarily slow,stride pattern to early
hominid bipedalism.
The anatomical evidence suggests australopithecine ground locomotion
was bipedal,but not necessarily of modern human form.
So much seems to be clear.
The anatomy of the upperlimb,such as the more cranially oriented
glenoid cavity and the curvature of the phalanges may indicate arboreality.
But from this you cannot deduce that they probably spent most
of their time moving arboreally.Chimpanzees are anatomically adapted
to arboreality but they spend most of the daytime on the ground.
I'm curious about Oxnards anatomical evidence.