The Morrison Formation is a geological formation located in the western United States, primarily known for its rich deposits of dinosaur fossils. It dates back to the late Jurassic period, approximately 155 to 150 million years ago. The formation consists mainly of sedimentary rocks, including sandstone, siltstone, and claystone, which were deposited in a variety of environments, such as river floodplains and lakes. This formation is particularly famous for its diverse array of dinosaur species, including Apatosaurus, Stegosaurus, and Allosaurus. The fossils found in the Morrison Formation have provided significant insights into the ecosystems of the Jurassic period, making it a key area for paleontological research and education.