The newly-discovered fossilized footprints were made by at least two mammalian species around 58 million years ago in a brackish water lagoon in what is now southern Wyoming, the United States, and may represent the earliest evidence of mammals gathering by the sea. Section of the 58-million-year-old tracksite demonstrating near-vertical tilting of the originally horizontal bedding with three separate trackways made by five-toed mammals walking in...
