New alligatoroid paper as example for amateur cladists

["Jonathan R. Wagner" <znc14@TTACS.TTU.EDU>]

        It seems not enough has been said on this list about the new
alligatorid paper which accompanied the CD-ROM CAT scanned 'gator skull in
the latest JVP (authored by the list's very own Dr. Chris Brochu, who should
STOP reading at this point so my nose doesn't turn brown...). Maybe this is
because it isn't about dinosaurs. I haven't had the chance to go through the
paper completely (and I guess I won't for a while, what with my own
research), but I thought I'd throw a few comments in and maybe try to sell
it to y'all. I think it might prove a good model for those on the list who
like doing amateur phylogenetic reconstructions.
        First and formost, the format of the paper is less formal than most
phylogenetic studies I've read, and relatively easy to follow. Topics are
introduced in a casual, almost conversational fashion, but the accompanying
discussions appear rigorous and complete (at least, to my non-crocodilian
eye). The ramifications of the analysis are dealt with explicitly and fairly
completely, rather than relying on the (inexperienced, in my case) reader to
draw conclusions.
        The phylogenetic analysis is huge, with numerous characters and a
bewildering array of taxa. I do not really know much about many of the
parameters involved, such as how to evaluate bootstrap support (I'm not sure
I even understand the ramifications of bootstrapping a cladisic matrix), but
the text provides a simple, convincing interpretation of the results. The
author did far more than simply present cladograms, and the thought process
shown here is a good example for those who haven't yet gotten the complete
swing of cladistics. The node-by-node breakdown looks less tedious than
others I've seen, but I'll have to really read it to make sure.
        By far the coolest part of the paper is the attention given to key
characters. Labelled figures walk you through the most important diagnostic
characters in enough detail that I personally would feel comfortable
evaluating their coding for a specimen. In fact, the monograph is overall
very well illustrated, enough so that a non-croc enthusiast like myself
feels comfortable reading the text and rarely gets lost.
        Phylogenetic taxonomy is followed by this paper, and at first glance
the usage appears agreeable. Those of you out there who think cladists need
to name every node should read this paper carefully. Again, I have not read
closely, but it appears that a great deal of thought and care went into the
conversion of old taxa to PT taxa, and consideration was given to the
original intentions of the namer. I had not yet seen genera defined using
PT; it certainly was an interesting choice. If nothing else, the author
clearly approaches PT as something other than a vehicle for advancing his
own immortality. We can only hope that other workers follow such a
conscientuous approach.
        There is one confusing taxonomic aspect, regarding the treatment of
the evaluation of monophly. The author concludes that he has found certain
taxa to be monophyletic, yet these taxa were defined as monophyletic taxa. I
may have missed a sentence or two explaining this. If there isn't one, let
me try to clarify, as this very statement has lead to confusion on this list
in the past. I believe that this means that the typological content- or
character-based taxon of the same name has been demonstrated to constitute a
monophyletic subset of all the taxa in the analysis. It is sort of like
saying "Dinosauria was found to be monophyletic" to mean "all the guys we
used to call saurischians and ornithiscians prove to form a monophyletic
group exclusive of other taxa."
        Those of us who are not Steve Irwin may want to keep a reference
handy to sort through all the extant (and extinct!) crocodilians while
reading (not that there isn't a fairly good discussion of these, they just
might get confusing if you don't dig on crocs), but it is not at all
necessary. Even if you aren't into crocs or phylogeny per se, the paper has
some interesting tidbits, including the conclusion that _Deinosuchus_ (by
far a personal favorite of mine) was an alligatoroid, not a crocodiloid.
        And, of course, the high point of the paper, indeed the volume, is
the excellent picture of Wann Langston on the first leaf. Now, if only it
had "Don't Panic" written in large friendly letters on the cover... :)

        Wagner

        
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     Jonathan R. Wagner, Dept. of Geosciences, TTU, Lubbock, TX 79409-1053
 "Only those whose life is short can truly believe that love is forever"-Lorien