The Age of Reptile developed a wide variety of monsters in the central regions of the continent from Montana to the Gulf of Mexico. The dinosaurs of the Triassic and Jurassic periods sometimes had gigantic size, the Brontosaurus attaining a length of sixty feet or more. The femur of the Brachiosaurus exceeded six feet; this must have been the greatest of them all. The greater dinosaurs were herbivorous. The carnivorous species were not remarkable for size; there were small leaping forms scarcely larger than rabbits. The necessity for defense against the flesh-eaters developed, in the smaller dinosaurs, extremely heavy armor. The stegosaur carried huge plates upon his curved back, suggesting a circular saw; his long powerful tail was armed with sharp spikes, and must have been a dangerous weapon. Dinosaurs roamed all over what is now called our middle west. In those days the central part of our land was warm and swampy. Fresh-water lagoons and sluggish streams were bordered by low forests of palms and ferns; one must go to the tropics to find a corresponding landscape in our times. The waters abounded in reptiles and fish. Huge winged reptiles flew from cover to cover. The first birds were evolving from reptilian forms. The absorbing story of these times is written in the rocks. The life forms were at their full when the sands were laid which to-day is the wide-spread layer of sandstone which geologists call the Morrison formation. Erosion has exposed this sandstone in several parts of the western United States, and many have been the interesting glimpses it has afforded of that strange period so many millions of years ago. In the Uintah Basin of northwestern Utah, a region of bad lands crossed by the Green River on its way to the Colorado and the Grand Canyon, the Morrison strata have been bent upward at an angle of sixty degrees or more and then cut through, exposing their entire depth. The country is extremely rough and bare. Only in occasional widely separated bottoms has irrigation made farming possible; elsewhere nothing grows upon the bald hillsides. Here, eighteen miles east of the town of Vernal, eighty acres of the exposed Morrison strata were set aside in 1915 as the Dinosaur National Monument. These acres have already yielded a very large collection of skeletons. Since 1908 the Carnegie Museum of Pittsburgh has been gathering specimens of the greatest importance. The only complete skeleton of a dinosaur ever found was taken out in 1909. The work of quarrying and removal is done with the utmost care. The rock is chiselled away in thin layers, as no one can tell when an invaluable relic may be found. As fast as bones are detached, they are covered with plaster of Paris and so wrapped that breakage becomes impossible. Two years were required to unearth the skeleton of a brontosaurus.