These tentative hints come from growth rings in cross sections of bone, like those in tree trunks – markings that show how the animal"s growth pattern varied from year to year. If growth stops, such as during hibernation, the gap leaves a ring. According to Druckenmiller, these distinctive bands have been found in several dinosaurs from the slopes of the Colville River, some of which may have hibernated. This adds to the evidence from elsewhere that dinosaurs may have had at least some of the adaptations required, such as burrowing.