Although this is a scientific publication on the fauna of the Green River Formation, it is the best and most complete publication regarding these fossils. The descriptions of the different fishes can be difficult for the layman to understand. There is also a large section devoted to vertebrates other than fishes including: birds, reptiles, mammals and sections on invertebrates and plants. There is a glossary to help with the terminology, a great bibliography and nearly 200 photographs and illustrations.