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Re: Re: Transitional Fossils



>
>A phylogenetic tree (or dendrogram) is homeomorphic to its parent cladogram.
>The stratigraphic and other information incorporated into the phylogenetic
>tree simply informs us about how to deform the cladogram to fit onto a
>geological chart. Stratigraphic information cannot change the topology of the
>cladogram.
>
BUT

In a phylogeny (as opposed to a cladogram), a potential ancestor (i.e., a
metataxon which occured earlier than its sister-group/descendants) can be
placed AS an ancestor (i.e., with the descendants arise directly from the
top of the range of the ancestor, not off to the side).

For example, a modern phylogeny of the Homininae could have the species of
Australopithecus, Paranthropus, and Homo deriving directly out of
Ardipithecus, and not out of some hypothetical side branch.

Or, in other words:

When you have potential ancestors, Use Them!

[This message brought to you by the Cladistic League for Anti-Defamation,
Eastern branch.]

Thomas R. Holtz, Jr.
Vertebrate Paleontologist
Dept. of Geology
University of Maryland
College Park, MD  20742
Email:Thomas_R_HOLTZ@umail.umd.edu (th81)
Fax: 301-314-9661
Phone:301-405-4084