Hell Creek Formation: Five Key Fossil Discoveries from North America's Legendary Cretaceous Site

The Hell Creek Formation, a geological site spanning eastern Montana, the Dakotas, and Wyoming, preserves fossils from 66 to 68 million years ago. Barnum Brown first excavated Tyrannosaurus rex bones there in 1902, naming the species in 1905. This formation contains over 95% of known T. rex museum specimens, with institutions like the Museum of the Rockies and American Museum of Natural History housing extensive collections. Beyond dinosaurs, the site includes the K-Pg boundary layer marking the asteroid impact that caused the Cretaceous-Paleogene extinction. Plant fossils reveal forests with palms, magnolias, and cycads, while small species like Acheroraptor temertyorum, discovered in 2013, indicate diverse ecosystems. In 2023, pterosaur remains were identified as Infernodrakon hastacollis, adding to the site's significance. The formation provides crucial context for understanding life before and after the mass extinction.