Hell Creek: last dinosaurs of Montana and Dakota
Montana's 68 to 66-million-year-old Hell Creek holds Tyrannosaurus and Triceratops below the final extinction clay.
68 to 66 million years on the coastal plain
Between 68 and 66 million years ago rivers crossed a warm coastal plain in Montana, Dakota and Wyoming, laying mud and sand that became the 100 meter thick Hell Creek Formation.
Ranchers and paleontologists find bones in badlands gullies every summer, with over 100 dinosaur sites mapped across 1000 square kilometers of outcrop in two states.
Tyrannosaurus neighbours and the clay line on top
Tyrannosaurus rex reached 12 meters and 8 tons here, living beside Triceratops with 3 horns, Ankylosaurus with armor plates, Edmontosaurus herds and pachycephalosaurs with 25 centimeter domes.
A thin 2 centimeter clay layer caps the formation everywhere, marking the 66 million year asteroid impact that ended 75 percent of species within months and defines the best dinosaur hunting in America.
- Age 68 to 66 million years in Late Cretaceous
- Tyrannosaurus 12 meters long and 8 tons heavy
- Triceratops Ankylosaurus Edmontosaurus together
- Impact clay 2 centimeters thick on top
- Over 100 bone sites across 2 states