The fiftieth anniversary edition of a landmark publication showcasing prehistoric North American landscapes and ecosystems, from a celebrated paleontologist at Yale University's Peabody Museum The fiftieth anniversary edition of John H. Ostrom's Stratigraphy and Paleontology of the Cloverly Formation revisits his groundbreaking work pinpointing the age of the continental sequence of the Bighorn Basin area in Wyoming and Montana. The Cloverly Formation is important for understanding the development of North American terrestrial landscapes and prehistoric ecosystems, and current investigations are reinterpreting the age of the Formation with new evidence and data. The reissue of Ostrom's original benchmark research offers contemporary relevance for researchers and students today.