Re: [dinosaur] Diadectomorphs and seymouriamorphs as amniotes from inner ear morphology

["David Marjanovic" <david.marjanovic@gmx.at>]

> Disagree. The standard usage of "stem-" in invertebrate paleo refers to 
> members outside the crown group but closer to it than to the next closest 
> crown group (so stem-arthropod, stem-mollusk, etc.). But "non-crown amniotes" 
> is (as noted) a nonsensical term.

But "members of a taxon, but not of its crown-group" is exactly what 
"stem-group" has meant ever since Hennig. I don't think I've seen phylogenetic 
definitions for Arthropoda or Mollusca, and Arthropoda at least is usually 
treated as having an apomorphy-based definition (it's not clear if even the 
trilobites are crown-group arthropods, but they're not going to be kicked out 
of Arthropoda!), so there are non-crown arthropods = stem-arthropods.