Reptilia; dispelling "delusions"

["Ken Kinman" <kinman@hotmail.com>]

> Why not treat both living and extinct animals the same?  Why differentiate
> at all?
> -Demetrios Vital
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    I agree for the most part.  We can't really treat them "exactly" the 
same, but both living and extinct groups should obviously be integrated into 
a single classification (and treated the same to the degree that the 
evidence will allow).  Therefore, I don't like crown group definitions for 
taxa, because they *do* over-emphasize the living groups.  "Living" vs. 
"extinct" is clearly a lousy character distinction (and phylogenetic 
"anchoring" definitions in general unfortunately use taxa rather than 
characters---now that's what I call arbitrary).
     In vertebrates, osteological characters obviously give us the best way 
to classify overall.  That is why scientists have long characterized 
Mammalia using the transformation of certain jaw bones into the three ear 
ossicles (rather than using hair or endothermy, or anything else the fossil 
record rarely preserves).  I would like to see that same thing happen to 
Aves---based on osteology (not a crown group or phylogenetically anchored).
     THIS all brings us to the Reptilia problem that is also being 
discussed on the list today.  However one defines Mammalia and Aves, the 
traditional Reptilia is simply all basal amniotes excluding the two exgroups 
Mammalia and Aves.  Reptilia have a common ancestor (first amniote), so 
although excluding two exgroups is admittedly arbitrary, it is still 
natural, useful, and has a long tradition as well.  The really dumb thing 
about traditional classifications is that they often fail to explicitly 
label such paraphyletic groups as such (and should include markers for the 
exgroups, as Benton has begun doing).  Anyway, the traditional synapsids 
(pelycosaurs and therapsids) are simply the "mammal-like" reptiles which had 
not yet evolved the mammalian jaw and ear ossicles.
     If only we had such an osteological character complex which clearly 
distinguished birds (incl. dromaeosaurs and various other traditional 
theropods) from the "bird-like reptiles" (i.e. "primitive" theropods).  In 
my opinion that would be the most effective way to battle Feduccia's BAND 
crusade.  It would also free us from the blurry distinction which 
Archaeopteryx has slowly forced upon us (i.e., regarding it as the first 
bird has outlived it usefulness and has become a liability instead).
              -----Ken Kinman


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