How paleontologists interpret the fossil record could be set to change, as new research demonstrates that floodwaters alter the disposition of bones in ways that run counter to decades of understanding.
During flood events, dinosaur and mammal bones are transported from their original locations by raging waters and buried elsewhere before becoming fossils. Researchers at the University of Minnesota Twin Cities reported their discovery of flood-based fossil transport in a recent paper published in Paleobiology.
An Unpredictable Environment
Decades ago, scientists conducted foundational research that is still used to understand how water flow affects bone transport prior to fossilization. Unfortunately, that work was limited in scope, focusing solely on typical river-flow conditions and not accounting for periodic disruptions. Despite a lack of technical understanding of how flooding affects bone placement, researchers have repeatedly invoked flooding to explain animal burials.
The new work focuses on the types of singular flooding events that can greatly alter the disposition of materials in sediment. To better understand this, they tested how bones move under the unsteady flow dynamics common in natural sheet floods.
“Paleontologists try to piece together the stories of how fossil sites actually came to be, sort of CSI style,” said lead author Michael Chiappone, a University of Minnesota Ph.D. candidate. “So we asked ourselves: ‘Are fossil organisms preserved in the places where they died? Or are we finding them after they’ve been moved some distance after death by scavengers or water flow?’”
Hellbound and Down 