[Taxacom] Orrorin a hominid?

[Kenneth Kinman]

Dear All,
      One paper which indicates that Orrorin should be placed near
Australopithecus in Hominidae (sensu stricto) is Richmond and Jungers
paper (March 2008 in the journal Science) on the femoral structure of
Orrorin.  They make a good case that it was bipedal.  I believe the case
for bipedality in Ardipithecus is still based on single toe bones (and
that argument seems more of a stretch to me).
      And of course, we know that Orrorin also had thicker tooth enamel,
like Australopithecus, whereas Ardipithecus has thinner enamel like
chimps.
      The one thing that still troubles me about Orrorin is its canine
tooth, which is very chimp-like.  I just wonder if perhaps the earliest
hominids might have been sexually dimorphic in this character.  Perhaps
males of Orrorin still retained a chimp-like canine, but the females had
already begun the reduction of this tooth.  As far as I know, we still
only have a single canine tooth from Orrorin, but I am hoping for more
material to be discovered.
            ---------Ken Kinman