Re: More on Digit Loss in Theropods

["Tim Williams" <tijawi@hotmail.com>]

Dan Varner wrote:

> >        Tim, I think I buy that for troodontids, but the velociraptors in 
> > the
> Fighting Dinosaurs exhibit showed a digit 2 in the same plane as 3 and 4. 
> The
> only hyperflexed 2 was stuck in the Protoceratops.

Nevertheless, it is possible (?likely) that the sickle-claw-bearing digit of 
dromaeosaurids was held off the ground during walking and running, but held 
in the same plane as digits 3 and 4 during rest.

>  I'm watching a Great Blue Heron right now

Dan, you're making me jealous.  My office doesn't even have a window.
:-(

> that leaves a distinctive
> hallux trace in its track. Roadrunners, too, I think.

I wrote: "Many terrestrial and aquatic birds (i.e. birds that do not perch 
in trees) show an abbreviated, elevated or non-existent hallux."

Herons are aquatic birds that often perch on branches, so it makes sense 
that they retain a useful hallux.  (Though it is true that a large hallux is 
not necessarily essential for perching in all birds.)

Roadrunners can also perch.  They have a zygodactyl foot - after all, they 
belong to the cuckoo family (Cuculidae, Cuculiformes).  Though they spend 
most of the time on the ground (such as when feeding/hunting), and are poor 
fliers, roadrunners do roost, especially in cool weather.


Tim

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