Re: "Reptilia"

[John Alroy <jack@homebrew.uchicago.edu>]

Just a couple of minor points on the continuing  
Friesen/Schwimmer/whoever debate.

1) Egg-laying mammals (such as platypuses) and toothed birds (such as  
Archaeopteryx) have been around since the middle of the 19th century.  
There is nothing radical about this usage. What IS poorly established  
on grounds of priority is whether the non-mammalian synapsids should  
be called "reptiles"; if we do, as most early/mid-20th century  
workers did, we get a grossly paraphyletic "Reptilia" (see below). If  
we don't, we end up with a term that is largely redundant with  
Diapsida or Sauropsida. 


2) To me, Friesen's arguments about what groups should be called  
classes and what groups are too "small" for the honor proves once  
again that the entire notion of Linnean ranks just should not be  
applied to fossils. The important things to convey in a  
classification are a) the branching order, b) how sure we are about  
that branching order, and c) something about the size of  
morphological/ecological gaps among groups. Trying to use the same  
ranking system for, say, Carboniferous animals and their descendants  
just confuses matters instead of helping us to do any of those  
things.

3) I think there IS a straight-forward distinction between  
"routinely" paraphyletic and "grossly" paraphyletic. Groups fall in  
the first category when they are "missing" exactly one branch (e.g.,  
Dinosauria is "routinely" paraphyletic if you exclude Aves from it);  
they are "grossly" paraphyletic when multiple subgroups have been  
split off, and I think in this discussion of "Reptilia" what gets the  
goat of people like me and Schwimmer is that "Reptilia" has been  
"grossly" hacked up like a gerry-mandered congressional district just  
to make sure "improved" amniotes like mammals and birds aren't  
included in it. And who says turtles aren't "improved"?! Sheesh...