hominid classification

[John Grehan]

At 10:06 AM 8/9/04 -0500, Ken Kinman wrote:

>       HOWEVER, a lot has happened in the past three years, and I am now a
> lot more skeptical about the lability of enamel thickness (as well as the
> evidence for bipedality in the scanty material of Orrorin).

Trouble is, that its not just a matter of enamel thickness. Along with
enamel thickness is the flattened surface of molar teeth in humans,
orangutans, australopithecines, and Orrorin (apparently).

What is the basis for your 'skepticism' on enamel.

>I don't know if more material for Orrorin has come to light, but there
>certainly is a lot more Ardipithecus material that will be described in
>the next few years.  Evidence from other body areas should help clarify
>the potential problem of parallelism in enamel thickness (and perhaps
>bipedality as well).

In what way?


>       If Orrorin and/or Ardipithecus get thrown in with Australopithecus,
> so be it.  I doubt that will be necessary.

It would be problematic for trying to lump Ardipithecus with
Australopithecus as their molars are completely different.

>But I will NOT accept a chopping up of Australopithecus due to
>paraphylophobia.  And by the way, a paraphyletic Australopithecus needs no
>synapomorphies since it is not a clade.  (Australopithecus + Homo) is
>presumably a clade and DOES require synapomorphies.

Agreed about Australopithecus not having a synapmorphy of its own if it is
paraphyletic - in which case it does not exist as a distinct lineage. But
there appear to be no synapomorphies other than bipedalism for
Australopithecus plus Homo

>The additional Ardipithecus material will allow more complete cladistic
>analysis and will probably answer a lot of questions.

Or it might not.

>P.S.  I am really trying to keep an open mind about the orangutan-human
>relationship, but I haven't found any molecular evidence supporting it
>(and I have tried) and you still have not presented any either.

You have decided that DNA base sequence similarities are the necessary
proof of phylogeny in which case of course no other evidence has any
bearing on the matter. Maryellen Ruvolo shares exactly the same view.

>Attacking the chimp-human molecular evidence won't get the job done.  You
>have to find some molecular support or your morphological data will just
>be dismissed.

This is a read herring for human evolution as the molecular stuff cannot
address the phylogeny of fossil forms. Just dismissing morphology as having
no weight against DNA base sequence similarities means that all fossils are
uninformative - completely. Might as well be a creationist.

John Grehan