By Alex Fox/Smithsonianmag.com
A group of polished, ancient stones found in Wyoming may have been carried more than 600 miles in the huge bellies of plant-eating dinosaurs, reports Ashley Piccone for Wyoming Public Radio. The findings, published last month in the journal Terra Nova, could provide a new line of evidence that dinosaurs may have undertaken long overland migrations.
Discovered near Wyoming’s Bighorn Basin in a geologic feature called the Morrison formation, researchers say these smooth, fist-sized rocks are gastroliths, which are rocks swallowed by dinosaurs—and some modern birds and reptiles—that may help grind up fibrous food.
A father-son geology duo collected the proposed gastroliths in 2017 during field research because the stones’ shiny appearance looked out of place surrounded by the fine-grained mud-rock that predominates the Morrison, reports Lucas Joel for the New York Times.
“We were walking around just doing some fieldwork in the Bighorn Basin,” Joshua Malone, a PhD student in geology at the University of Texas at Austin and the study’s lead author, tells Wyoming Public Radio. “We started seeing these polished stones and we were like, ‘those look pretty exotic compared to all the other rock around us.'”