Meeting Abstract
Dinosaur footprints are trace fossils documenting the interaction of live animals with deformable substrates. Some tracks are relatively accurate molds of the foot, but most are not. Factors such as substrate consistency and foot motion are known to give rise to disparate track morphologies that may differ considerably from static pedal anatomy. Although typically viewed as surfaces, any given track is a sample of a broader, often hidden, volumetric phenomenon. Some specimens of deep tracks can be split into multiple slabs, revealing evidence of foot movement into and out of the sediment. We used CT imaging to reconstruct internal surfaces of deep tracks from the Early Jurassic (~200 MYA) of the Connecticut Valley. Our first glimpse inside these fossils reveals that natural breaks, mechanical splitting, and subsequent preparation have significantly damaged most exposed surfaces. In particular, elevated features documenting foot withdrawal were either too fragile to survive or were mistakenly removed. Such topographic structures are key to understanding how deep tracks formed and explaining the origin of footprint disparity. CT data enable us to more clearly observe the results of foot-sediment interactions than is possible from exposed surfaces alone, and serve as key constraints on reconstructions of extinct dinosaur limb kinematics.
