Re: data

Harry Erwin (
Sun, 06 Aug 1995 20:25:20 -0400

In article <400b3h$>, alex duncan
<> wrote:

> In article <3vr5m1$> HARRY R. ERWIN,
> writes:
> >: maxillary sinus: absent
> >--found in a source
> What source?

No luck. Oxnard didn't address it, although he did discuss a strange
aspect to the Gig. data sample--very high sexual dimorphism, yet even
(1-1) sex ratio in the sampled population. Neither Groves nor Simons say
anything, either. I have to assume this is an error that crept into the
database in the usual fashion.

> I was unaware that there were any Giganto maxillae
> preserved. Please keep in mind that a lot of what's available out there
> presents the ASSUMPTIONS of the authors. A lot of Andrews' work on
> hominoid cladistics contains assumed character states. A rule I've
> always tried to follow is that I don't use a character unless I have the
> material to back it up with, e.g., Peter Andrews lists as a possible
> synapomorphy of Pan & Homo "angle of ear bones over 90 degrees." I'm not
> sure what "earbones" he's talking about, or how the angle was measured,
> so I don't use the character.

I'm getting there really quickly, especially after reading remarkably
opposed assessments of the Ouranopithecus material today.

> The state of phylogenetic analysis for
> primates leaves a lot to be desired compared to what we see for other
> groups. I suspect most vertebrate paleontolgists have a good old time
> when they see what the anthropologists are up to.
> >I've got a source for that one, since it wasn't defaulted. I'll look at
> >home tonight. I suspect it was Oxnard, since I don't remember seeing it in
> >Simons or Groves last night. In any case, it has no effect, since the rest
> >of the apes in that little clade have the opposite polarity.
> >: To get back to the case of Giganto, you're assuming that it has a lot of
> >: character states that are similar to those seen in Pongo and Siva, even
> >: though these parts aren't represented in the fossil record. I feel
> >: confident that those assumptions are effecting the position of Giganto in
> >: your cladogram.
> >
> >It didn't. Sorry.
> You mention in another post that you think the characters that link
> Giganto and Pongo are homoplastic. What characters (other than body
> size) are you referring to?

Sexual dimorphism (since it's much clearer for Gig than for Siva), incisor
crown height. There's also the point that Gig. is not united with Pongo in
opposition to Siva, but rather in opposition to a clade consisting of
Siva, Rama, and Lufengpithecus. I think the key characteristic in causing
this to happen is size, although turning that off still didn't abolish
what was happening.

> (All of a sudden I realize that it must seem as if I have a violent
> prejudice against Giganto being in a clade w/ Pongo. I really don't, I
> just find the results surprising given that Siva has so many potential
> synapomorphies w/ Pongo, and most of the characters that link Siva and
> Pongo simply aren't known for Giganto.)

My take is that Gig. is a big Siva, taken to extreme, but I can't figure
out how to tell the program that.

> Alex Duncan
> Dept. of Anthropology
> University of Texas at Austin
> Austin, TX 78712-1086
> 512-471-4206

Harry Erwin
Home Page: (try again if necessary)
PhD student in comp neurosci: "Glitches happen" & "Meaning is emotional"