re: birds & crocs

[@lepomis.psych.upenn.edu, @uga.cc.uga.edu:Schwimm@USCN.BITNET (Paleontology Columbus College, Georgia)]

A bit more on the subject:

  Larry Martin at U. Kansas indeed champions the hypothesis that
birds and crocodilians are close sister taxa, rather than that
dinosaurs/birds are essentially part of a monophyletic clade.  Much of
his argument stems from the manner of tooth replacement in crocodilians
and (Mesozoic) birds, which is vertical rather than alternately
oblique as in squamates and theropods.  In other words, he has  set
up the hypothesis that tooth replacement mode is a critical apomorphy
which uniquely defines the dichotomy between bird/croc descent and
theropods.  Several others at U.K. follow this logic, including a
colleague with whom I work and with whom I have had heated arguments
suggesting that tooth replacement has no overriding significance to
justify ignoring the host of other obvious dinosaur-bird synapo-
moprphies.

   Parenthetically, at the museum in Kansas (Lawrence) is a reconstruction
by Martin of Archaeopteryx as a running maniraptorian-like dinosaur. Go figure.

david schwimmer
columbus college
schwimm@uscn.cc.uga.edu