Animals Before Man in North America: Their Lives and Times

abundant amphibians ancestors ancient anomodonts appearance armor back-bone beasts beds birds bison bones bony brain bulk Camarasaurus camel Carboniferous carnivorous changes climate continent Coryphodon crabs creatures creodonts Cretaceous crinoids crocodiles developed Devonian dinosaurs Diplodocus early elephant Eocene Europe existence extinct feet in length feet long fins fishes foot footprints forms fossils genus groups of animals habits hind horns horse ichthyosaurs inches invertebrates jaws Jurassic known labyrinthodonts land larger largest legs living lower mals mammals mammoth Marsh Mastodon Miocene modern mosasaurs Museum natural North America Ornithostoma past period Permian Phenacodus plates plesiosaurs Pliocene portion present preserved prey probably Professor Cope pterodactyls race relatives represented reptiles resemblances rocks saurs seems shape sharks shells skeleton skull sloths smaller South species specimens spines structure tail teeth Thespesius tion titanotheres to-day tooth Trias Triassic Triceratops trilobites ture turtle tusks vertebrates wings