new hominid

John Grehan jgrehan at SCIENCEBUFF.ORG
Mon Nov 1 08:55:34 CST 2004


Ken,

Thanks for the interview citation. Brown makes some interesting comments
regarding phylogenetic affinity which are interesting because of their
apparent vagueness. I offer some comment on this below, but until I see
the paper itself (hopefully this week) it is not possible for me to
judge.

Brown said:

"On initial examination I was impressed by the features it appeared to
share with early [hominids] like Australopithecus, but other features
were more like Homo. For instance, australopithecines have large,
projecting facial skeletons (large molar and premolar teeth in
particular), whereas the face of LB1 is much more similar to members of
the genus Homo. So you have this very humanlike looking face stuck with
this very, very small braincase--a brain size which would be small for a
chimpanzee. Looking at the rest of the skeleton, it had a combination of
things we would consider to be humanlike features combined with things
which are found in some australopithecines. I decided that some of the
similarities with australopithecines were probably due to small body
size and the biomechanics of locomotion, rather than just representing
phylogeny. In other words, it wasn't an australopithecine located in
Asia. And other things, like thickened bone in the cranial vault and the
shape of the brain case, are more like those in members of the genus
Homo than like Australopithecus. So I dismissed Australopithecus for a
variety of reasons and then did a balancing act. And when we thought
that it was most likely a dwarfed example of Homo erectus, then I leaned
toward putting it in the genus Homo rather than creating a new genus."

I hope there is something far more substantive in the paper itself, but
the above paragraph seems to indicate a phylogenetic assignment on the
basis of overall similarity ('balancing act'). The skeleton looked 'more
like' species currently in Homo so that's where it went. If Homo is not
monophyletic then that assignment might be problematic so it is
important as to whether the new fossil shares synapomorphies with Homo
as a whole if one is to sort out the phylogenetic lineage of hominids.
There are also various skulls classified as Homo erectus that do not
conform to the type so that derivation might be problematic also. 

I'm admit be being quite envious that one is allowed to make up new taxa
in hominid systematics simply as a 'balancing act'. It would make my
life a whole lot easier if I could do that with insects.

I'll be interested to see how this all plays out.

John Grehan



> -----Original Message-----
> From: Taxacom Discussion List [mailto:TAXACOM at LISTSERV.NHM.KU.EDU] On
> Behalf Of Ken Kinman
> Sent: Sunday, October 31, 2004 10:16 PM
> To: TAXACOM at LISTSERV.NHM.KU.EDU
> Subject: Re: [TAXACOM] new hominid
> 
> Responding to John Grehan's last post.  It isn't really necessary that
> _floresiensis_ shares autapomorphies with genus Homo as a whole
> (especially if there are no such skeletal autapomorphies YET known for
> genus Homo).
> 
>      In fact, I would actually PREFER autapomorphies it shares with
some
> subclade of Homo----either Homo erectus + sapiens, or better yet with
Homo
> erectus (sensu lato) alone.
>            ------- Ken
> P.S.  Here is a link to an interview with Peter Brown about
floresiensis
> which might help to shed further light on this:
> 
> http://www.sciam.com/print_version.cfm?articleID=00082F87-7D35-117E-
> BD3583414B7F0000




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