Re: Morgan Tears 3.

David Froehlich (
Wed, 1 Nov 1995 14:20:16 -0600

On 30 Oct 1995, H. M. Hubey wrote:

> I mean, let's examine the facts. WE have some bones, and some of them
> resemble others. Some are large, and some are small. We look at the
> whole bunch and then try to trace out some kind of a family tree
> based on not much more than gazing at the bones, and imagining some
> getting larger and some smaller, some bones stretching and chaning
> morphology, etc.

My God! A serious question that actually deserves a reply! Wow!

In all seriousness, the prpblem is quite complex and I do not actually
have the time at present to tutor you on comparative anatomy,
phylogenetic methodology, homology and related subjects. If you truly
interested please reference the Journals, Systematic Biology (was
Systematic Zoology, Systematic Botany, and Cladistics. The methodology
is quite clear and reproducable.

> The last time I even imagined a problem close to this was a matching
> or a clustering problem. Given n objects with a single measurement
> for each object try to put them in some kind of an order of
> "relatedness" based on some kind of difference or distance.

This is a gross simplification of the problem. Are you actually asking
whether or not any fossil organism can be placed in a phylogenetic tree?
If so, yes with certain qualifications and an unknown amount of uncertainty.

> IF these were statistical problems what kind of level of confidence
> would you place on these statements? Or is this "science" still
> some distance from even realizing the complexity of the problem
> and the possibility of errors creeping into the bone similarity
> matches? The more I think, the more curious I get. Are complete
> skeletons of some of these putative ancestors and their
> close relations available in all cases, or is the middle filled
> in via lots of imagination and hope.

You seem to want proof. This is not available ina historic science since
time machines do not exist. All we can say is that given all of the data
this is our best guess, provisional only on new information.

To answer your first question, yes we do know that the last common
ancestor of the proboscideans and the carnivores is something akin to the
primitive morphology for all therian mammals (small, pointy teeth,
probably insectivourous given the pointy teeth, etc) There is a broad
range of information, both fossil, soft anatomical from modern organisms,
and biomoloecular that supports this contention. (No it is not all
"bone-gazing", but since you have no interest or understanding of what
that entails, you can scoff all you want).

David J. Froehlich Phone: 512-471-6088
Vertebrate Paleontology Laboratory Fax: 512-471-5973
J.J. Pickle Research Campus
The University of Texas, Austin, Texas 78712