Re: Tetanurae

["T. Michael Keesey" <keesey@gmail.com>]

On 12/8/06, Jamie Stearns <stearns5@cox.net> wrote:
> Stem-based:

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)

Hehe.

> 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
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