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Re: Say this slowly: theropoda is paraphylitic, theropoda is paraphlyitic.....



At 08:55 AM 6/26/00 -0400, ELurio@aol.com wrote:

Let's see, I get told that the term  paraphyletic is actually the term
polyphyletic.
right then you tell me that it isn't. Hmmmmm......
The two terms have different meanings. A paraphyletic group is one that includes the most recent common ancestor of all of its members and of each pair of members, but excludes one or more monophyletic groups of its descendents. A polyphyletic group is one that either does not include the common ancestor of all members, or does not include the common ancestor of some pair of members.

Thus a given the current best cladograms, _Theropoda_ *without* birds is paraphyletic. A Theropoda consisting of several disjoint clades each derived from a non-theropod ancestor would be polyphyletic.

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May the peace of God be with you.         sarima@ix.netcom.com