Re: First Family and AAT

Gerrit Hanenburg (
Sat, 14 Oct 1995 09:07:47 GMT

chris brochu <> wrote:

>Phylogenetically, there is one African biped and one Australian biped,
>since bipedalism arose only once in each case. Both lineages diverged in
>their past; Hominidae is now down to one species. Macropodidae is more
>diverse, but keep in mind - they've been bipedal for roughly 40 million

>You've actually asked a very interesting question - why is Hominidae not
>more diverse? Unfortunately, none of the hypotheses we are arguing here
>addresses this issue. True, forest bipeds (macropodids) are diverse, but
>so are semiaquatic bipeds. Ever look at a field guide to birds?
>Shorebirds are extremely diverse.

The reason for this might be the fact that humans are extremely eurytopic
(broad niched).Their situation is comparable with the antilope taxa
Aepycerotini (impalas) and Alcephalini (wildebeest,hartebeest,blesbuck
etc.) The Alcephalini are stenotopic (narrow niched or specialists).
The Alcephalini show high rates of speciation and extinction,and great
diversity of form.By contrast,the Aepycerotini are generalists,and have
persisted longer than the Alcephalines,but have shown little diversity of
form or number of species.
I don't know the macropodids well enough but I suspect that they are
specialists and that this may be the reason for their high species
My guess is that the Hominini from Homo erectus on (or maybe even
H.habilis) have become increasingly eurytopic and that this may be one of
the reasons for their low diversity.(like the impalas)