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On 12/8/06, Jamie Stearns <firstname.lastname@example.org> wrote:
Better to use "branch-based", as "stem" has another meaning in tree
terminology. (The latest draft of the PhyloCode uses "branch-based"
rather than "stem-based".)
This, as stated earlier, could create problems when abelisaurs
are taken into account.
I really don't see why this is a problem. If abelisaurs are
tetanurans, then they're tetanurans.
Node-based: Normally, this would be a good solution. However, this is also
problematic with things like Piatnitzkysaurus, Cryolophosaurus, etc.
floating around out there (laughs at ridiculous thought of 25-foot theropods
floating around in inner tubes)
Apomorphy-based: This may be more viable then the other two, as a popular
"rule of thumb" (no pun intended) places Tetanurae as "theropods with three
or fewer digits on hand." Unfortunately, as many of the big theropods have
dinky little arms that are rarely found, this comes with its own set of
problems. Nevertheless, a refined version of an apomorphy-based definition
that includes a few more characteristics may be the way to go.
Apart from the problems raised by you and Tim, it's kind of ridiculous
to base a clade whose name means "stiff tails" on a manual character!
If _Tetanurae_ were to be apomorphy-based at all (which is probably
not a great idea), it should be based on a caudal character.
But perhaps an apomorphy-based clade could be named for the
three-fingers clade. Is "Tridactyla" in use anywhere?
T. Michael Keesey
The Dinosauricon: http://dino.lm.com
Parry & Carney: http://parryandcarney.com
ISPN Forum: http://www.phylonames.org/forum/