Footprint formation and interpreting fossil dinosaur tracks

Brown University, Providence RI

Investigators

Abstract

New Title: Footprint formation and interpreting fossil dinosaur tracks Non-technical Abstract Dinosaur tracks offer unique evidence of the anatomy, behavior, and environment of long-extinct animals when they were alive. These tracks and trackways are recognized as unrivaled glimpses into dinosaur locomotion, recording aspects of gait, speed, limb posture, foot motion, and even social behavior. A single animal's tracks can vary dramatically depending on the firmness of the substrate and how deeply it sank with each step. This project aims to understand both the effects of substrate on locomotion and the origin of track diversity in the fossil record. 3-D movement of birds walking on different substrates will be measured using skeletal models animated using X-ray video. Computer simulations of track formation will reveal how tracks develop both at the surface and at different depths. These exciting new methods developed by the researchers for imaging, quantifying, and simulating locomotion through deformable substrates will provide an entirely new, volumetric perspective on the "birth" of a dinosaur track. Simulated bird tracks will then be compared to 200 million year old dinosaur tracks to help explain variation in shape and correct errors in previous interpretations. Results from this research will fundamentally change our perception and interpretation of dinosaur tracks by unlocking previously invisible motions and mechanisms. Technical Abstract Why are footprints shaped the way they are? How and why does a single animal produce a disparate array of tracks? The proposed project aims to continue a fruitful collaboration between Gatesy (paleontology, biomechanics, and functional anatomy) and Falkingham (computer science, geology, and paleontology). The PIs will explore the emergence of footprint morphology from the dynamic interplay between bipedal dinosaurs and deformable substrates. They seek to understand the origin and functional significance of Mesozoic track diversity by exploring disparate specimens in the historic Hitchcock Ichnology Collection at the Beneski Museum of Natural History at Amherst College. PIs will integrate living bird experiments (XROMM: X-ray Reconstruction of Moving Morphology) and substrate simulations (DEM: Discrete Element Method) to reveal important interactions among anatomy, motion, and sediment properties governing footprint formation. Volumetric DEM models of guineafowl tracks in varying substrates will serve as reference for interpreting and iteratively simulating specific specimens from the Connecticut Valley and Greenland. Results from this research will fundamentally change our perception and interpretation of dinosaur tracks by unlocking previously inaccessible foot/sediment dynamics.