Extreme foot development

[Martin Human <cockatoo@csi.com>]

Hi,

While watching Attenborough's "Life of Birds" I was struck (not
literally!) by the structure of the ostrich's foot, which has lost
several toes as an adaptation for running (it carries it's weight on two
toes, one being much larger than the other).

In the evolution of mammals this has happened too, and in the case of
the horse has gone one step (gah!) further.

Is there any known case of a dinosaur going to this extreme (they had
enough time after all) ? I know I
have seen drawings of hadrosaurs with a "hoof-like" foot, and indeed
have seen footprints of 3-toed dinosaurs which were supposed to be
iguanadon-like). Did any of the bipedal "fast runners" evolve in this
"single-toed" direction?

cheers, martin