Formation, preservation, and interpretation of dinosaur tracks

Abstract The fossilized tracks of dinosaurs were first reported in the scientific literature in 1836, not long after Buckland's discovery of Megalosaurus . Tracks record aspects of dinosaur locomotion, diversity, and ecology. To recover this information from a track requires an understanding of the track forming process. The interaction between foot anatomy, motion, and substrate means that diversity in track shape can indicate different trackmakers, but may also come from the same trackmaker moving across different environments, or in different ways. Being volumetric phenomena, diversity can also arise from how a track is exposed. Layers of sediment beneath the original sediment–air interface, that may or may not have directly interacted with the foot, can vary dramatically within a single track volume. Here, we describe the track forming process in detail, using examples from previous work with computer simulation and extant taxa, with a particular emphasis on how this can lead to an apparent increase in taxonomic diversity. We also present a novel advanced simulation of dinosaur foot motion derived from a fossil track, that builds on previous work. Motions previously determined from surface features are improved using CT scanning of internal track geometry. This reconstructed motion is then used to animate a virtual foot complete with phalangeal joints, claws, and textured skin, and the motion is tested against sediment simulations. Differences in morphology between fossil and simulation emphasize the complexities of track formation, and highlight that further work is required to fully understand the foot–sediment interaction.