These are fossils from the Green River Formation and were collected at the Fossil lake location in Wyoming. You are buying all four fossils. There is one species called "Diplomystus dentatus" located on the bottom right and the rest of them are a species called "Knightia eocaena". The fossils range from 3 inches to 4 inches long, the slabs are irregular. All the fossils have nice bone structure and some have good scale structure. The carbon color on all of them is awsome. These fossils would be great for a starter collection or for study or to make a wall mural. The fossils date back to the Eocene Period approximatly 50 million years ago.Thank you for looking and I do combine shipping to save you money. Check out my other items ! This will be the last of my listings until January.