Paleontologists working in the Morrison Formation, Utah, USA. This formation dates back to the Late Jurassic Period, which was approximately 155 to 148 million years ago. The area is known for its extensive fossil discoveries, particularly of dinosaurs and other ancient organisms. Most of the fossils are found in the green siltstone beds and lower sandstones, which are remnants of the rivers and floodplains of the Jurassic period.