[Supercryptid]

It's a commonly known fact that the cheetah (Acinonyx jubatus) is the fastest of the land animals (according to Wikipedia, it can reach speeds between 70 and 75 miles per hour). Has this always been the case? Are there any extinct animals that may have exceeded its speed?

I realize that you can't exactly put an extinct animal in a race and measure its speed, but can't an animal's possible speed be inferred based on its skeletal structure and analogies with living, related species?

I'd like to know what the calculated running speeds for the following extinct animals are, if such data exists: The American "cheetahs" (Miracinonyx inexpectatus and M. trumani), and an extinct, running hyena (Chasmaporthetes ossifragus).

Any other fast animals you can suggest would be appreciated (such as, perhaps, dinosaurs).

[another_someone]

Interestingly enough, I recently read about a dinosaur that has been dug up with part of its flesh fossilised (first time that has been found), and they found far more muscle on the animal than they had anticipated.  Just goes to show how difficult it is to make such calculations until you see the real thing (even then, they were not making any guesses about speed, only to say that they thought it would be higher than their present calculations might have expected).

[paul.fr]

Also interesting, is the fact that Bryan Habana (a rugby player) not too long ago raced a cheetah...and only just lost!

http://www.youtube.com/watch?v=7_iAQXyDJns&mode=related&search=

[Alandriel]

I've heard that peregrin falcons are even faster.

Or would you discount that as aerial vertebrae (vs terrestrial vertebrae) ? 

[Bored chemist]

The record for downhill skiers is faster than the cheetah too: are the people with planks on their feet "cheating"?