Re: smallest ANCIENT non-bird dinosaur - was what I was asking

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

On Fri, May 2, 2008 at 1:38 PM, David Marjanovic
<david.marjanovic@gmx.at> wrote:
>
> > A stem-X is not an X. But is more closely related to X than to
> > anything else alive.
>
>  I'd interpret it the other way around: a stem-X _is_ an X, it's just not
> part of the crown-group _of_ X. The trunk is part of a tree...

Then "X" starts to become quite vague.

In the past I have toyed with the idea that these old names perhaps
should remain vague, and whenever we want to be specific we should
preface them with "crown-", "pan-", or, if applicable, "apo-". I even
wrote up a short paper on the idea before deciding I didn't like it,
after all. The thought of names like "Aves", "Cetacea", etc. not
actually meaning anything on their own just seemed too strange (even
if it is compatible with how people use them).

If these names are forced to mean something, then I have to agree with
Gauthier that in general the crown group is best, as it limits
unwarranted inferences. For example, let _Cetacea_ refer to the crown
group, _Pan-Cetacea_ or pan-Cetacea to the total group,
"stem-cetaceans" to the stem group, and perhaps coin new names for
apomorphy-based clades ("Cetorrhini", "Cetopoda", "Cetoplota",
"Cetorachiopinnae", "Ceturopinnae", etc.).

>  Yes -- except if you're more interested in teeth and middle ears than in 
> gross shape. Then it becomes interesting.

And if you had a foot fetish you'd call _Coelophysis_ a bird....
-- 
T. Michael Keesey
Director of Technology
Exopolis, Inc.
2894 Rowena Avenue Ste. B
Los Angeles, California 90039
http://exopolis.com/
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