Re: synapomorphies not created equal

[Dinogeorge@aol.com]

In a message dated 9/1/01 3:20:35 PM EST, Mickey_Mortimer11@msn.com writes:

<< Not exactly.  Ornithischia is a stem group (all closer to Triceratops than
 Neornithes), so as long as a character isn't present in Dinosauria or more
 inclusive groups, it's a synapomorphy of Ornithischia.>>

No, it's just an >apomorphy< of Ornithischia.

Stem groups don't even have synapomorphies, since there is a part of the stem 
in which >none< of the apomorphies found further along in the group is 
expressed. Only subgroups within stem groups may have synapomorphies.

I find the concept of "synapomorphy" to be really quite dubious. Like common 
ancestors, synapomorphies must exist, but they're almost impossible to 
discover. The synapomorphy concept is a holdover from when clades were 
character-based rather than relational.