How did dinosaurs move?

Recent advances in computer technology allowed remarkably realistic animations of dinosaurs (and other creatures) in films. But how realistic are these animations?

In a recent feature, Danielle Venton of International Science Grid This Week (iSGTW) writes:

In a memorable scene from Steven Spielberg’s Jurassic Park, a Tyrannosaurus rex gallops behind a jeep, close to overtaking it, lunging to take a bite out of Jeff Goldblum — to the horrorified delight of millions of thrill-seeking movie-goers.

Assuming dinosaurs could be resurrected, how realistic would this situation be?

Not very, according to Karl Bates, a researcher in dinosaur locomotion. In fact, our scrawny-armed, prehistoric friend would probably have trouble outrunning a bicyclist. Depending on how fast you run, you may or may not be in trouble if you were on foot.

(...)

By his best guess, this dinosaur ran at about an average running speed of 15 miles per hour (24.5 kph) and would have walked at about 5.5 mph (9 kph), faster than the average humans — but not the fastest ones.

It turns out that muscle size is the single most important determinant for dinosaur speed. Since we know little about their actual muscle mass, there is a lot of guess work involved. But with these new high-performance models it is an educated guess. The model allows to study different scenarios in a physical environment, including gravity.