Like many 6-year-olds, Julian Gagnon likes to pick things up off the ground. Sticks, rocks, you name it. Earlier this month, he made his most important discovery yet. Important enough to garner the attention of University of Michigan’s Museum of Paleontology. Julian found an ancient mastodon tooth during a Sept. 6 hike with his family at Dinosaur Hill Nature Preserve in Rochester Hills. UM museum scientists verified its authenticity, and Julian will donate it to the museum to ensure its preservation. Julian is probably the first person to touch the tooth in 12,000 years, said Adam Rountrey, the paleontology museum’s...