FOSSILS A Story of the Rocks and Their Record of Prehistoric Life By Harvey C. Markman Curator of Geology and Paleontology Cover Design and Murals by Mary Chilton Gray DENVER MUSEUM OF NATURAL HISTORY Popular Series No. 3 Alfred M. Bailey, Editor Third Edition, Reprinted October 1, 1954 [Illustration: At Work on a Dinosaur Skeleton] CONTENTS Page Introduction 5 The Prehistoric Record 5 Varieties of Fossils 8 Fossilization 9 Floras and Faunas 13 Formations 16 Geological Time 18 Explanation of the Time Chart 23 The Geological Section 25 Before the Age of Reptiles 31 The Pre-Cambrian Complex 31 Cambrian Life 33 The Ordovician Record 35 Silurian Events 36 Devonian Progress 37 Carboniferous Forests 40 Permian Hardships 43 The Age of Reptiles 47 Dinosaurs 48 Plant Life and Climate 56 Coal and Fossil Footprints 57 Mesozoic Invertebrates 58 Extinct Birds 60 Ancestors of the Mammals 61 The Age of Mammals 64 Prehistoric Horses 70 Mastodons and Mammoths 80 The Rancho La Brea Fossil Pits 88 The Age of Man 93