New Study Finds Dinosaurs Ate Rocks, Migrated To Wyoming

Mar 15, 2021

One of the gastroliths found in the study. The camera lens is shown for scale.
Credit Joshua Malone

New research suggests that certain rocks in Wyoming might be there because of dinosaur migration.

Joshua Malone, a geoscience researcher at the University of Texas at Austin, noticed some unusual rocks while in Wyoming, which made him wonder how they got there.

"We were walking around just doing some fieldwork in the Bighorn Basin," he said. "We started seeing these polished stones and we were like, 'those look pretty exotic compared to all the other rock around us.'"

Many animals like crocodiles and seals eat rocks to help with digestion- they're called gastroliths. The rocks that the dinosaurs carried are recognizable to geologists because they are smooth, different from their surroundings, and near dinosaur remains.

Malone said the rocks are usually smaller than a human hand. The dinosaurs would die with them still in their stomachs. When their bodies decomposed, the rocks were exposed.

"We inferred that these were ingested in Wisconsin, or somewhere along this sluggish stream that was flowing from the east to the western United States during that time," he said. "We figured that once they were ingested, they were carried and eventually deposited out within the Morrison deposition."

This means dinosaurs migrated over 600 miles to Wyoming after eating the rocks. Scientists already knew that they migrated, but Malone said this technique is a new way to track that movement.

Have a question about this story? Please contact the reporter, Ashley Piccone, at apiccone@uwyo.edu.