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Re: [Sub]Arctometatarsalia



Nick Gardner (n_gardner637@hotmail.com)

<I wasn't aware that oviraptorids had subarctomets. I "thought" that
caenagnathids had arctomets but now I'm not sure. Could someone clear up
what taxa have subarctomets and which that have arctomets and those that
have hyperarctomets?>

  The subarctomet pes is properly applied to those taxa which bear a
pinched third metatarsal between the second and fourth, but is not
occluded from expression on the extensor or flexor surfaces of the
metatarsus itself. In this manner, the subarctomet pes is found in
Oviraptoridae, *Caudipteryx*, *Velociraptor* and *Deinonychus*,
*Nedcolbertia*, the unnamed Arkansas pes (in the *Nedcolbertia* paper),
and probably *Ornitholestes* as well.

  The hyperarctomet pes, on the other hand, refers to the derived
condition seen in taxa where the third metatarsal is reduced proximally
and does not ascend to the tarsus, and is not expressed in the proximal
metatarsus either extensorly or flexorly. This pes is found in
*Mononykus,* *Parvicursor,* and *Avimimus,* and apparently *Shuvuuia* as
well, but not *Alvarezsaurus.* I wrote to the list previously that the
metatarsal fragments known for *Patagonykus* do not appear to pertain to
the metatarsals II+IV, but to II+III, and in this manner, it would be
subarctomet, rather than arctomet or hyperarctomet.

  As noted before, the "normal" arctomet pes is known in Ornithomimidae,
*Garudimimus,* possibly *Harpymimus,* Tyrannosauridae, Troodontidae (incl.
*Sinovenator*), *Microraptor,* and *Sinornithosaurus.*

  *Archaeopteryx* and other Aves are not arctomet, subarctomet, or
hyperarctomet in any fashion. This is a reversal under nearly any possible
position for these taxa within Coelurosauria.

=====
Jaime A. Headden

  Little steps are often the hardest to take.  We are too used to making leaps 
in the face of adversity, that a simple skip is so hard to do.  We should all 
learn to walk soft, walk small, see the world around us rather than zoom by it.

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