The Eocene Period
There is no hard-and-fast line that can be drawn to mark the end of one geological period and the beginning of a new one. With a few exceptions, the various periods shade gradually into one another without any very abrupt change. However, the beginning of the Eocene period brought about such marked changes in the appearance of the world and its plant and animal life that it seems proper to regard this period as the beginning of a new era in the history of the earth.
Tremendous geological changes took place between the laying-down of the Cretaceous and the Eocene rocks. The Cretaceous rocks, during the greater part of the Cretaceous period, were beneath the water, some of them under the deep sea. In the Eocene, however, they, with all their lagoons, estuaries, lakes and seas, were generally forced up into dry land and mountain ranges. Not only were the chalky and clayey and sandy deposits of the Cretaceous raised above the level of the surrounding sea into such masses as the chalk cliffs of southern England and northern France, but even the floors of ancient seas were forced upwards, sometimes as high as 10,000 or 17,000 feet. It must have been a stupendous although gradual upheaval of the earth’s crust, for it took place all over the world.
When the Eocene deposits began to form, we find that not only was the face of the world completely changed, but its plant and animal life was unlike that of preceding periods. It is for this reason that the period has been called the Eocene, from the Greek word eos, meaning “dawn,” and it has been regarded as the beginning of a new system, which has been named the Tertiary. It was the dawn of the world as we know it to-day.
Eocene rocks are found all over the earth. In the Old World they are found chiefly in the Pyrenees, the Alps, the Carpathians, the Caucasus, Asia Minor, Northern Africa, Persia, Baluchistan, the Sulaiman Mountains, China and Japan. In eastern North America the Eocene rocks stretch along the Atlantic and all the way from New Jersey into Texas. In the interior of the continent there are large areas of Eocene rocks in Alberta, some in Saskatchewan, and in various parts of the central and western United States. There were shallow lakes and marshes and much volcanic activity in this region during the Eocene.
The vegetation of the period was very rich, and many of our common trees grew freely, as ashes, beeches, willows, poplars, elms and maples. Palms and bananas were also to be found. The climates of Alaska and Greenland were temperate, and luxuriant forests abounded in those regions.
The animal life of the period was varied. Mammals, birds, reptiles, fishes, insects and molluscs were well represented. Among the birds, snipes, seagulls, buzzards, hawks, ospreys, quails, pelicans, flamingoes and horn- bills were common. But the most striking feature of the Eocene animal life was the disappearance of the huge lizards of the Cretaceous period and the appearance of new and better developed mammals.
Just why the mighty race of dinosaurs died out is a mystery. The Eocene climate was cooler than that of the preceding period, and it may have been that these great reptiles could not stand the change in temperature. Perhaps the fact that the early mammals may have fed on dinosaur eggs had much to do with the reptiles’ rapid decrease in numbers and final and complete disappearance.
Two of the most extraordinary creatures living in the Eocene were the titanothere and the uintathere. The former appeared early in the Eocene as an animal no larger than a sheep, and gradually developed into a beast the size of a small elephant. The titanothere had a heavy body supported by thick legs. Two great bony lumps grew out of the front of the skull, and the brain was hardly as large as a man’s fist. For all their great size, the titanotheres must have been very stupid creatures.
The uintathere has been found only in America, where it was characteristic of the Eocene period. It also was as large as a small elephant, and was well armed with six stout horns, four above its nose and two above its ears. In the males the upper canines were developed into two long, sabre-like tusks. Like the titanothere, the uintathere had a ridiculously small brain within its bulky body.
Other mammals appearing in the Eocene were the ancestors of the horse, rhinoceros, tapir, pig, camel and monkey.
After the Eocene came the Oligocene, a period not very different from the Eocene. Oligocene rocks are not common east of the Mississippi except in the Gulf region. On the Pacific coast they are more common, however, and in the interior of the continent are large areas with many interesting fossils. In general the plants were like those of the Eocene, but the climate was cooler.
THE LARGEST MAMMAL THAT EVER WALKED THE EARTH
It was during the Oligocene that baluchitherium, the largest of land mammals, lived. The bones of this great beast were discovered in the hills of Baluchistan in southern Asia. It stood from twelve to thirteen feet high at the shoulder, and by lifting its head and stretching, it could eat leaves twenty feet above the ground. It was a distant relative of the modern rhinoceros with which we are all familiar.
The Miocene followed the Oligocene. Miocene rocks are found in France, Belgium, Switzerland and in many other countries, and show a gradual progression in all forms of life, together with the production of many new forms. In western North America Miocene rocks are widespread, but they are not very thick except on the Pacific coast.
The most remarkable of the new animals were the mastodon and the dinotherium, both huge beasts of the elephant family. The tusks of the mastodon were straight; those of the dinotherium turned downward. The first mastodon was discovered in 1613, and the history of its discovery is very curious, one of the rare examples of imposture in science.
THE SURGEON WHO DECEIVED THE WORLD OF SCIENCE
The skeleton was found by some workmen in a sand quarry at Dauphiny, in France. Such bones had never been found before, and a surgeon called Mazuyer saw a chance of making a great sensation. He purchased the bones and then pretended that he had found them in a tomb thirty feet long and fifteen feet broad, built of bricks, and bearing the inscription: “Teutobocchus Rex.” He also stated that he had found fifty medals of Marius in the tomb; and there seemed no reason to doubt his apparent good faith.
A barbarian king named Teutobocchus had actually invaded Gaul at the head of the Cimbri, had been defeated by the Roman Marius and led in triumph to Rome. According to tradition, Teutobocchus was so tall that he towered above all the trophies borne on the lances of the soldiers in the triumphal procession. Mazuyer’s story therefore fitted in perfectly with the legend and met with general acceptance. The giant formed out of the mastodon’s bones was twenty-five feet long, and the skeleton was exhibited throughout France and Germany. A great many people were rather skeptical, and a learned anatomist argued that the bones belonged to an elephant; but it was not until they were removed to the Museum of Natural History in Paris that the remains were actually identified as the skeleton of a creature like an elephant.
The dinotherium, found only in Europe and India, was larger than either the mastodon or the mammoth. It lived on herbage, and seems to have inhabited lakes.
In the Miocene, cats, and hogs and antelopes were also found. Wolves, panthers and sabre-tooth tigers were common.
The whole Tertiary period may be considered as the age of mammalian rise and domination, just as the Secondary period was the age of the rule of the great reptiles.
