_ARCHAEOPTERYX_ vs. _CAUDIPTERYX_

["Ralph Miller III" <gbabcock@best.com>]

I hate to interrupt the "Evolution of Bird" discussion, but it brings to
mind a puzzle.

I recently walked a class of first graders through some of the flight
adaptations seen in modern birds and some of the most obvious differences
between the skeleton of a crow (as seen in an illustration) and the
skeleton of _Archaeopteryx lithographica_ (represented by a skeletal
reconstruction illustration and a copy of the Berlin specimen).  I did what
I could to make the one brief session as interactive and hands-on as
possible.

As much as I would like to introduce first and second grade kids to the
highly derived feathered theropod, _Caudipteryx_, and help them to discover
for themselves why it is not considered a bird according to Ji, Currie, et
al. (whereas _Archaeopteryx_ is an established, card-carrying member of
Aves), I am afraid that the differences are so subtle that the kids won't
be able to see them.  Can anyone pinpoint for me any critical and obvious
characteristics -- which are evident from a cursory examination of the
fossil specimens -- that separate the above taxa and help to establish
which is a member of Aves and which is not?  My feeling from reading the
pertinent dinosaur mailing list posts and the recent _Nature_ article is
that in these examples the line between avian and non-avian would be too
fine for youngsters to grasp.  Would you agree?

I could instead fall back to _Sinosauropteryx prima_ as an example of a
(proto)feathered non-avian theropod, which would make the concepts more
self-evident.  Clarity is important to me, because I want the kids to feel
a sense of being involved in the process of comparing the anatomy, and, of
course, I don't want them to have too hard a time of it or they'll get
frustrated and revolt.  They haven't taken any graduate courses in anatomy,
and, neither, for that matter, have I (sad to say).

-- Ralph Miller III     gbabcock@best.com 

And if you had to fight them off with a well-armed platoon of marines,
which animal would put up the better fight?  ;^)