Part 1 (1/2)

Dinosaurs.

by William Diller Matthew.

PREFACE.

This volume is in large part a reprint of various popular descriptions and notices in the American Museum Journal and elsewhere by Professor Henry Fairfield Osborn, Mr. Barnum Brown, and the writer. There has been a considerable demand for these articles which are now mostly out of print. In reprinting it seemed best to combine and supplement them so as to make a consecutive and intelligible account of the Dinosaur collections in the Museum. The original notices are quoted verbatim; for the remainder of the text the present writer is responsible.

Professor S.W. Williston of Chicago University has kindly contributed a chapter--all too brief--describing the first discoveries of dinosaurs in the Western formations that have since yielded so large a harvest.

The photographs of American Museum specimens are by Mr. A.E. Anderson; the field photographs by various Museum expeditions; the restorations by Mr. Charles R. Knight. Most of these ill.u.s.trations have been published elsewhere by Professor Osborn, Mr. Brown and others. The diagrams, figs. 1-9, 24, 25, 37 and 40, are my own.

W. D. M.

CHAPTER I.

THE AGE OF REPTILES.

ITS ANTIQUITY, DURATION AND SIGNIFICANCE IN GEOLOGIC HISTORY.

Palaeontology deals with the History of Life. Its time is measured in geologic epochs and periods, in millions of years instead of centuries. Man, by this measure, is but a creature of yesterday--his ”forty centuries of civilization”[1] but a pa.s.sing episode. It is by no means easy for us to adjust our perspective to the immensely long s.p.a.ces of time involved in geological evolution. We are apt to think of all these extinct animals merely as prehistoric--to imagine them all living at the same time and contending with our cave-dwelling ancestors for the mastery of the earth.

In order to understand the place of the Dinosaurs in world-history, we must first get some idea of the length of geologic periods and the immense s.p.a.ce of time separating one extinct fauna from another.

_The Age of Man._ Prehistoric time, as it is commonly understood, is the time when barbaric and savage tribes of men inhabited the world but before civilization began, and earlier than the written records on which history is based. This corresponds roughly to the Pleistocene epoch of geology; it is included along with the much shorter time during which civilization has existed, in the latest and shortest of the geological periods, the Quaternary. It was the age of the mammoth and the mastodon, the megatherium and Irish deer and of other quadrupeds large and small which are now extinct; but most of its animals were the same species as now exist. It was marked by the great episode of the Ice Age, when considerable parts of the earth's surface were buried under immense acc.u.mulations of ice, remnants of which are still with us in the icy covering of Greenland and Antarctica.

_The Age of Mammals._ Before this period was a very much longer one--at least thirty times as long--during which modern quadrupeds were slowly evolving from small and primitive ancestors into their present variety of form and size. This is the Tertiary Period or Age of Mammals. Through this long period we can trace step by step the successive stages through which the ancestors of horses, camels, elephants, rhinoceroses, etc., were gradually converted into their present form in adaptation to their various habits and environment.

And with them were slowly evolved various kinds of quadrupeds whose descendants do not now exist, the t.i.tanotheres, Elotheres, Oreodonts, etc., extinct races which have not survived to our time. Man, as such, had not yet come into existence, nor are we able to trace any direct and complete line of ancestry among the fossil species known to us; but his collateral ancestors were represented by the fossil species of monkeys and lemurs of the Tertiary period.

[Ill.u.s.tration: Fig. 1.--The Later Ages of Geologic Time.]

_The Age of Reptiles._ Preceding the Age of Mammals lies a long vista of geologic periods of which the later ones are marked by the dominance of Reptiles, and are grouped together as the Age of Reptiles or Mesozoic Era. This was the reign of the Dinosaurs, and in it we are introduced to a world of life so different from that of today that we might well imagine ourselves upon another planet.

None of the ordinary quadrupeds with which we are familiar then existed, nor any related to nor resembling them. But in their place were reptiles large and small, carnivorous and herbivorous, walking, swimming and even flying.

_Crocodiles, Turtles and Sea Reptiles._ The Crocodiles and Turtles of the swamps were not so very different from their modern descendants; there were also sea-crocodiles, sea-turtles, huge marine lizards (Mosasaurs) with flippers instead of feet; and another group of great marine reptiles (Plesiosaurs) somewhat like sea-turtles but with long neck and toothed jaws and without any carapace. These various kinds of sea-reptiles took the place of the great sea mammals of modern times (which were evolved during the Age of Mammals); of whales and dolphins, seals and walruses, and manatees.

_Pterodactyls._ The flying Reptiles or Pterosaurians, partly took the place of birds, and most of them were of small size. Strange bat-winged creatures, the wing membrane stretched on the enormously elongated fourth finger, they are of all extinct reptiles the least understood, the most difficult to reconstruct and visualize as they were in life.

_Dinosaurs._ The land reptiles were chiefly Dinosaurs, a group which flourished throughout the Age of Reptiles and became extinct at its close. ”Dinosaur” is a general term which covers as wide a variety in size and appearance as ”Quadruped” among modern animals. And the Dinosaurs in the Age of Reptiles occupied about the same place in nature as the larger quadrupeds do today. They have been called the Giant Reptiles, for those we know most about were gigantic in size, but there were also numerous smaller kinds, the smallest no larger than a cat. All of them had short, compact bodies, long tails, and long legs for a reptile, and instead of crawling, they walked or ran, sometimes upon all fours, more generally upon the hind limbs, like ostriches, the long tail balancing the weight of the body. Some modern lizards run this way on occasion, especially if they are in a hurry.

But the bodies of lizards are too long and their limbs too small and slender for this to be the usual mode of progress, as it seems to have been among the Dinosaurs.

ANIMALS OF THE AGE OF REPTILES.

LAND REPTILES.

DINOSAURS corresponding to the larger quadrupeds or land mammals of today.

CROCODILES, LIZARDS AND TURTLES still surviving.

SEA REPTILES.