Montana Governor and First Lady's Math and Science Initiative
Landslide Butte
Secondary 213, near Del Bonita Port of Entry
In 1912 Smithsonian geologist Eugene Stebinger and paleontologist Charles Gilmore came to Blackfeet Country looking for dinosaur remains. Their search took them to a badland area near Landslide Butte, a prominent landform near the Milk River to the east of here. Stebinger named the sandstone and mudstone rock unit the Two Medicine Formation, and determined that it was nearly 2000 feet thick, representing a geological time span from 74 to 80 million years ago. From this formation, Gilmore collected and named 3 new species of dinosaurs. A second paleontological group from the Museum of the Rockies here in Montana, led by Jack Horner, explored this same area from 1985 through 1987, and discovered an additional 4 new species of dinosaurs, including one of the largest dinosaur nesting grounds on earth, covering nearly 6 square miles. In addition, enormous bonebeds of duck-billed dinosaurs and horned dinosaurs supported theories that these kinds of dinosaurs traveled in gigantic herds, and may have migrated along the eastern front of the ancient Rocky Mountains. Three of the dinosaurs, known exclusively from this one area, are the horned dinosaurs Rubeosaurus, Einiosaurus, and Achelousaurus, hypothesized to represent an evolutionary sequence of transitional species.
