Re: ARCTOMETATARSALY

[<twilliams@canr1.cag.uconn.edu>]

> Yes, arctometatarsality *requires* that mt III is pinched between mts II and
> IV, is reduced in thickness proximally, and consequently is less exposed on
> the dorsal surface of the metatarsus than II or IV.

The basal ornithomimosaur _Harpymimus okladnikovi_ is clearly not 
arctometatarsalian, although mt III is slightly attenuated 
proximally.  Assuming that _Harpymimus_'s referral to the 
Ornithomimosauria is correct, is it possible that arctometatarsaly 
evolved independently by the Bullatosauria (Troodontidae + 
Ornithomimosauria) and Tyrannosauridae?
  
As an aside, the tantalizingly-undescribed "Tonouchisaurus" - mentioned more 
than 
once on this list as an Early Cretaceous tyrannosaur - reportedly also 
has a non-arctometatarsalian foot.

Tim Williams  

>