Rachel Laker is a 5th year graduate student who studies marine vertebrate taphonomy. She investigates how the duration of taphonomic susceptibility impacts bone preservation.
Sequence stratigraphy provides a framework to predict sedimentation (or burial) rate – hiatal or erosional surfaces serve as periods of prolonged exposure to taphonomic agents, while systems tracts bury bones at a more rapid rate, resulting in a comparatively shorter window for taphonomic alteration.
She examines microbial tunnels and authigenic minerals that form in the early post-mortem window primarily through traditional petrographic analysis, and has found relationships between tunneling extent, tunnel morphology, and authigenic mineral microfacies and assemblages, as a function of stratigraphic position. Her findings show that bones reliably record their post-mortem environment, and that these signals are consistent across different depositional basins. Scrappy and fragmentary fossil material can serve as helpful indicators of depositional environment, especially when the stratigraphic context is difficult to interpret. Although most of her samples are from museum collections, Rachel also conducts her own field work in Big Bend National Park (Texas).