Re: Therizinosauria Cladogram

[Dinogeorge@aol.com]

In a message dated 1/11/02 1:49:50 PM Pacific Standard Time, 
tmk@dinosauricon.com writes:

<< Well, then it is different than _Therizinosauria_, since it couldn't have
 included _Alxasaurus_ or _Beipiaosaurus_ or _Nothronychus_, etc.
 
 Membership does not equal definition, anyway. >>

Well, nobody has even >published< the name Therizinosauria yet, let alone 
defined the taxon. And all those later genera were simply added to the 
original Segnosauria when they were classified in or close to the families 
contained in Segnosauria. You might say the original definition was modified 
by the addition of the newly described genera. After all, that's what taxa 
are defined for in biology: to be used, not to be discarded when a new 
taxonomic fashion or a new genus comes along.

It is ridiculous to expect taxa defined in the years prior to the 
introduction of cladistics to be defined cladistically, and it is a gross 
injustice to pre-cladistic taxonomists to throw out their taxa as undefined 
just because they happen not to have phylogenetic definitions. Old taxa can 
always be given phylogenetic definitions based on their included taxa and 
thereby be preserved in line with the current taxonomic fashion. After all, 
wasn't Nopcsa's Thyreophora resurrected for ankylosaurs and stegosaurs after 
falling into disuse? Nopcsa certainly provided no phylogenetic definition for 
Thyreophora (and he put ceratopians in it, too).

There is a need for a name for the stem group that comprises Eshanosaurus 
through Therizinosaurus, and such a name, Segnosauria, is already available. 
There is no need to create the new name Therizinosauria for this group.