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*To*: Stanley Friesen <sarima@ix.netcom.com>*Subject*: Re: Fixing dinosaurian carnivour question*From*: "T. Mike Keesey" <tkeese1@gl.umbc.edu>*Date*: Mon, 7 Jun 1999 21:43:53 -0400 (EDT)*Cc*: dinosaur@usc.edu*In-reply-to*: <4.1.19990606153929.00970100@popd.netcruiser>*Reply-to*: "T. Mike Keesey" <tkeese1@gl.umbc.edu>*Sender*: owner-dinosaur@usc.edu

On Sun, 6 Jun 1999, Stanley Friesen wrote: > A *quick* summary: > > 1. Derive a cladogram by any of the usual methods. > > 2. Annotate each internode with a measure of the change it represents (its > length) > - the simplest, but often least useful, measure is simply the number of > synapomorphies on it. > - a slightly more sophisticated variant is to weight the synapomorphies > inversely by their frequency on the cladogram (thus a unique synapomorphy > has the highest weight, and a highly convergent character has very low > weight). > - more sophisticated measures can be devised, as desired. > > 3. At any given taxonomic rank, "cut" the cladogram at those internodes > having a weighted length greater than a selected threshold - perhaps using > some statistical measure of significance or information content to > determine the threshold value. Interesting! Of course, it does look a bit hard to apply on a large scale... Although I find virtually no utility in ranking taxa, this practice actually could come in handy for me -- namely in figuring out the optimal way to divvy up the taxon pages on my site. In anticipation of the site's revival (September at the latest), I have been preparing a new version with more taxon pages, e.g. where I once had Ornithothoraces & Neornithes, I now have Enantiornithes, Ornithurae, Hesperornithiformes, and Neornithes. I've been (mildly) agonizing over where it would be best to draw such arbitrary cuts, but perhaps this method could be of use. Now if only there were a recent cladistic analysis (with character matrix) of all Ornithodira ... --T. Mike Keesey <tkeese1@gl.umbc.edu> WORLDS <http://www.gl.umbc.edu/~tkeese1> THE DINOSAURICON <http://dinosaur.umbc.edu>

**Follow-Ups**:**Re: Fixing dinosaurian carnivour question***From:*Stanley Friesen <sarima@ix.netcom.com>

**References**:**Re: Fixing dinosaurian carnivour question***From:*Stanley Friesen <sarima@ix.netcom.com>

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