Dinosaur Speed Estimator
How fast did dinosaurs run? Paleontologists estimate dinosaur speeds from fossilized trackways using Alexander's formula, which relates stride length to hip height. This calculator uses the same method to estimate speed from trackway measurements. Enter the stride length and either hip height directly or footprint length (used to estimate hip height).
How We Calculate This
Speed v = 0.25 × √g × SL^1.67 × h^(-1.17) (Alexander 1976), where g = 9.80665 m/s², SL is stride length in metres, and h is hip height in metres. Hip height from footprint: h ≈ 4 × footprint length.
Frequently Asked Questions
What is Alexander's formula?
R. McNeill Alexander developed a formula in 1976 to estimate animal speed from trackways: v = 0.25 × g^0.5 × SL^1.67 × h^(-1.17), where g is gravity, SL is stride length, and h is hip height.
How do we know hip height from footprints?
A common approximation is that hip height ≈ 4 × footprint length. This ratio varies between species but provides a reasonable estimate when direct measurements aren't available.
How accurate is this method?
Alexander's formula was derived from observations of modern animals and provides reasonable estimates, but has uncertainties of 20-30%. Dinosaur body proportions may have differed from modern animals.
What does stride length tell us about gait?
The ratio of stride length to hip height indicates gait. SL/h < 2.0 suggests walking, 2.0-2.9 suggests trotting, and > 2.9 suggests running. Very high ratios indicate galloping.
How fast was T-Rex?
Estimates for T-Rex maximum speed range from 17-29 km/h (11-18 mph). Recent biomechanical studies suggest they may have been limited to brisk walking rather than high-speed running.
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