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Re: Question about hominids (from 'Ardi')

> I understand that birds have the 'backwards knee' that's
> really their ankle that makes how they walk different from
> us, but tyrannosaurids and hadrosaurids, and other dinosaurs,
> had the forward knee - how is their locomotion different from
> hominids?

All digitigrade animals I can think of have "backwards knees" (really
ankles), such as tyrannosaurids, hadrosaurids, cats, dogs, cattle and
horse, and not only birds. We can be unique in being a plantigrade
biped (for more steps than most other primates and bears) but I am not
sure about gibons.

>> I'm especially curious because somebody on the show (can't
>> remember who) made the claim that bipeds are going to be less
>> agile and less speedy than quadrapeds. Wouldn't most
>> tyrannosaurids disagree?

As far as I know, only a few quadrupeds, including cheetah, pronghorn
and lion, are faster than the ostrich. The movement of the vertebral
column in the sagittal plane helps increasing the velocity of some
mammals, but the ostrich is faster than the greyhound which does this
movement. Anyway, I would not say that as a whole bipeds are slower. I
do not think this assertion can resist some statistical analysis.
Regarding agility, it seems as difficult to define. In any case, birds
can move very fast and have fast reflexes (many birds hunt venomous
snakes, for example).