Bipedalism and arboreality

[James Norton <JNorton@MAILBOX.UNE.EDU>]

>>> Rob Meyerson <rjmeyer@ix.netcom.com> 04/06/98 05:34pm >>>
>In a message dated 98-04-03 03:17:17 EST, rjmeyer@ix.netcom.com
writes:
>
I do have one problem with the idea of bipedalism evolving completely in
the trees: for an arboreal animal to become completely bipedal, it will
have to let go of the branch with it's front limbs.  It's hands would have to
let go, if it is to stand up.  <<<<

As suggested in an earlier post, it's easier to imagine an animal that is
already a biped and that possess the requisite balance moving into the
trees to perch on branches than it is to imagine a quadruped learning to
let go with its front limbs and become bipedal in the trees.

On the other hand (no pun intended), it's also easy to imagine an arboreal
creature with four grasping limbs moving out of the trees onto the
ground, exapting the grasping forelimbs for manipulation of prey or
environment and returning the hindlimbs to a terrestrial locomotor function
(as in human evolution).  Devlopment of grasping limbs in the trees,
return to the ground to develop bipedalism, back into the trees again to
develop flight - sounds complicated but may have been just the
one-in-a-million combination of events that led to the evolution of avian
flight.

JM Norton