Known as gastroliths, the pieces of pink quartzite have revealed that long-necked sauropods most likely swallowed them (maybe to grind the tough plant matter they ate) as they migrated to their own Great Valley. “We interpret that these gastroliths were ingested by dinosaurs, most likely sauropods, in the Laurentian midcontinent and then transported in their digestive tracts to the site of deposition,” said Joshua Malone, a grad student at the Jackson school of Geosciences at the University of Texas at Austin, who recently led a study published in Terra. Before Wyoming or Wisconsin or hu...