Could dinosaurs walk or run? In 1975, legendary biomechanics professor R. McNeill Alexander provided a simple formula that allows palaeontologists to calculate the running speed of any animal, including a dinosaur, from its trackway.

The faster you run, the longer your stride – knowing that, the formula requires a measurement of gravity, a measurement of stride length, and a measurement of the height of the hip (= leg length) of the perpetrator. Real tracks show most dinosaurs dawdled, strolled, or at best, walked at a smart clip. Only the really small dinosaurs could actually run.

[Left] Reconstructed hind limbs of T. rex, showing the main hindlimb muscles. This is the basis for biomechanical study. [Image courtesy of Bill Sellers, Manchester.]

Now, using digital methods, biomechanics experts such as John Hutchinson (Royal Veterinary College, London) and Bill Sellers (University of Manchester) can reconstruct the limbs and muscles of Tyrannosaurus rex, or any dinosaur, calculate muscle sizes and capabilities, and animate their running. What does this tell us? Read the book to find out!