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Re: Transitional Fossils



In a message dated 95-10-03 14:23:53 EDT, Thomas_R_HOLTZ@umail.umd.edu (th81)
writes:

>AHA!  I think I've found the crux of the problem here...
>
>I think we are talking about different things.  Although many people (myself
>included) will  refer to a cladogram as a phylogeny, it is not actually
>such.  A cladogram is a graphic representation of the distribution of
>derived character states among taxa.  A phylogeny is the next step, the
>transformation of a cladogram into a representation of the "family tree",
>including stratigraphic and other data.  This distinction (between
>cladograms and phylogenies) is address in almost every technical primer on
>cladistics.
>
>So, stratigraphy and biogeography are not used in the cladistic analysis per
>se, but in the transformation of the resultant cladogram into a proposed
>phylogeny.

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.