I have heard a claim that the elephant is the only animal with 4 knees.

However, I also seem to remember an explanation (maybe even from this site, though I can't find it...) that only 2 of an elephant's knees are technically knees.

What appear to act as knees have in fact evolved from some other joint. (Elbows, perhaps?)

As you can tell, I am floundering! Can anyone clarify the facts for me?

Thanks in advance!

Nick

Elephants, like all tetrapods, only have two knees (i.e. joints of the hindlimb that bend forwards). They have joints in their forelimbs that bend backwards, but those are the equivalent of our wrist joints. There is a nice picture of an elephant skeleton here (http://en.wikipedia.org/wiki/File:Elephant_skeleton.jpg) in which you can clearly tell which joint is which.