Humans Running at Stadiums and Beaches and the Accuracy of Speed Estimations from Fossil Trackways

Abstract

The concept of dynamic similarity between mechanical properties of vertebrates and engineered structures has served in previous work to suggest that there is a power law relationship between vertebrate speeds and stride length. This relationship, with some additional assumptions about hind limb height, has permitted the calculation of speeds from fossil trackways of dinosaurs. However, there are claims that uncertainties are large. In this work we analyze the accuracy of speed calculations for fossil vertebrates based on fossil trackways by using data derived from both athletic competitions and an experiment with humans walking and running on a beach. Our results show that although there are somewhat different running regimes, in general terms human speed can be described in a simple way, and differences between observed and predicted speeds usually are no more than 10–15%. Thus, while recognizing that some uncertainty remains in the estimation of hind limb height, we conclude that reliable speed calculations can be obtained from vertebrate fossil trackways. Our results also show that very reliable speed estimates can be obtained from human fossil trackways directly from stride length measurements.