Why is it that four-footed animals...?

Question

Do not have a curve of spee http://en.wikipedia.org/wiki/Curve_of_spee in their dentition, unlike people (who are obviously two-footed)? Curve of spee is the curve that starts from the upper canine until the upper molars. I just need a logical explanation for this. I've been thinking that maybe it's because humans can only move their lower jaw, but I'm not sure if four-footed animals can move their maxilla (upper part of mouth) and if this has anything to do with curve of spee.

Here's a pic by the way:

http://www.tpub.com/dental1/14274_files/image134.jpg

I appreciate your opinions! =)

Answer 1

Logically... because those lower to the ground (usually) don't have large mastication muscles that control the force of the bite and angle of the chew.

Because we don't bite off from roots and trees we need the extra muscles to control the angle of our down force and chew.

This is also why Dogs, cats, etc eat smaller bites, and usually remove the food from the dish and eat it off the floor and why larger quadrupeds like giraffe's use their tongues to rip and pull food into their mouths.

If you think about it, it is actually the bi-pedal's who are at a disadvantage.