Dinosauria

“ The Dinosauria, a group of extinct reptiles, containing the genera Iguanodon, Hadrosaurus, Megalosaurus, Poikilopleuron, Scelidosaurus, Plateosaurus, &c., which occur throughout the whole series of the Mesozoic rocks, and are for the most part of gigantic size, appear to me to furnish the required conditions. ”

“ Even in point of etymological appropriateness, the term "Dinosauria" is no more fitting for reptiles of which some are small, than "Pachypoda" is for reptiles of which some have slender feet; but as Von Meyer's name has never obtained much currency, it may be well to allow justice to give way to expediency, and to retain the name of Dinosauria for those reptiles which agree in all the most important and characteristic parts of their structure with Megalosaurus and Iguanodon. ”

“ If the tibia without that epiphysis and the astragalus were found in the fossil state, I know not by what test they could be distinguished from the bones of a Dinosaurian. And if the whole hind quarters, from the ilium to the toes, of a half-hatched chicken could be suddenly enlarged, ossified, and fossilized as they are, they would furnish us with the last step of the transition between Birds and Reptiles; for there would be nothing in their characters to prevent us from referring them to the Dinosauria. ”

“ While the geological range of the Dinosauria, according to present knowledge, is confined entirely to the Mesozoic period, known so well as the Age of Reptiles, their geographical distribution was extensive. America, Europe, Asia, Africa, and Australia, have all contributed remains of these animals, but "while North America seems to have contained the greatest number of different types, some of the larger species are now known to have lived in the southern half of the continent. Europe stands next to America in variety and number of these reptiles, large and small." ”

“ The skull as it lay in the rock measured more than six feet in length, four feet in width, and the horn-cores about three feet in height. These dimensions far surpass any of the Dinosauria hitherto known, and indicate to some extent the wonderful development these reptiles attained before their extinction at the close of the Cretaceous. ”

“ The other figures on the same plate (4, 5) represent the distal end of a femur, the posterior face of the outer condyle of which exhibits the remains of the ridge which plays between the tibia and the fibula, and is so characteristic of the Dinosauria among reptiles. ”

“ The Ornithomorpha arranged in this way show that the three middle groups—carnivorous Saurischia, Aristosuchia, herbivorous Ornithischia—which are usually united as Dinosauria, intervene between Birds and Ornithosaurs; and that the Crocodilia and Ornithosauria are parallel groups which are connected with Birds, by the group of Dinosaurs, which resembles Birds most closely. ”

“ The further evidence as to the ornithic affinities of the Dinosauria which I have to bring forward in the present paper consists, first, in the structure of the pelvis, as shown by Megalosaurus, Iguanodon, and Hypsilophodon, and, secondly, in that of the distal end of the tibia and of the astragalus, as evidenced by Poikilopleuron, Megalosaurus, and Lælaps.
If the pelvis of any existing reptile be compared with that of any existing bird, the following points of difference will be observed:—
1. In the Reptile the ilium is not prolonged in front of the acetabulum ”

“ It may be said that all birds stand upon their hinder feet, and that, as the Ornithoscelida did the same, the resemblance of structure arises from a resemblance of function. But I doubt if the majority of the Dinosauria stood more habitually upon their hind limbs than Kangaroos or Jerboas do ”

“ Art. XIV.—Description Of New Dinosaurian Reptiles by O. C. Marsh. (With Plate 1.)
Recent explorations in the West have resulted in the discovery of many remains of Dinosaurs, some of which are of more than ordinary interest. A few are from the Jurassic, but most of them are from the Cretaceous, especially from the upper portion, in the so called Laramie formation. Those found in the latter horizon show a high degree of specialization, and present some anatomical features not before observed in this group of reptiles. ”

“ Either the Dinosaurian Reptiles must have survived to a later period in South America than elsewhere, or geologists must have been mistaken as to the age of the formation in which the other reptiles and extinct mammals occurred. ”

“ Beds of the same age occur in the Rocky Mountains of North America, containing abundance of Dinosaurians and other reptiles, among which is the Atlantosaurus, the largest land-animal yet known to have existed on the earth. ”

“ In habits the dinosaurs were terrestrial, and often amphibious, and the structure of the tail in some genera indicates its use as a swimming organ. Some were of graceful, bird-like action, walking, running, or leaping on their three-toed hind limbs. Others were heavy, clumsy beasts, walking or crawling on their solidly built four legs. Dinosaurs vary greatly in size. The smallest are of the size of a chicken. The largest are the greatest land animals ever known to have existed, with lengths of 60 to 70 feet, heights of 10 to 20 feet, and weights estimated to have varied from 20 to 25 tons. ”

“ Dinosaurs appeared in the early Triassic time, and during the Jurassic and Cretaceous periods they ruled the land, but toward the end of the Cretaceous they began to decline, and they finally gave way to the early mammals. ”

“ The dentition of dinosaurs is fitted for both carnivorous and herbivorous food. Beak-like structure of the jaws is common. The teeth are often implanted in sockets and in some genera they appear in successional series. The head of dinosaurs is usually disproportionately small, and the brain is always of very small size and low degree of convolution, indicating an inferior grade of intelligence in these animals. ”

“ At Dinosaur National Monument only Morrison rocks of the upper Jurassic Period contain the fossil bones of dinosaurs. After Morrison time, the Cretaceous seas invaded this area. More than 5,000 feet of sandstone, shale, and mudstone were formed from sediments deposited in these seas.
Elsewhere in North America and the rest of the world, the diversity and numbers of dinosaurs actually increased. Entirely new groups evolved and achieved success in the battle for survival. The climax of reptile development seems to have come near the end of Cretaceous time in the Mesozoic Era. ”

“ They may be classed in three divisions,—the flesh-eating dinosaurs, the reptile-footed dinosaurs, and the beaked dinosaurs,—the latter two divisions being herbivorous.
The flesh-eating dinosaurs are the oldest known division of the order, and their characteristics are shown in Figure 329. As a class, reptiles are egg layers (oviparous) ; but some of the flesh- eating dinosaurs are known to have been viviparous, i.e. to have brought forth their young alive. This group was the longest-lived of any of the three, beginning in the Trias and continuing to the close of the Mesozoic era. ”

“ Dinosaurs, which were contemporary with Ornithosaurs, approximate to them in blending characters of Birds with the structure of a Reptile and something of a Mammal in one animal. If an Ornithosaur is Reptilian in its backbone, in the articular ends of each vertebra having the cup in front and ball behind in the manner of Crocodiles, Serpents, and many Lizards, a Dinosaur like Iguanodon, which had the reversed condition of ball in front and cup behind in its early vertebræ, may be more Mammalian than Avian in a corresponding resemblance of the bones to the neck in hoofed Mammals. ”

“ The answer has been given to us by their bones, as studied by Yon Meyer and Owen, and more recently by Huxley and Cope. We thus have brought before us the Dinosaurs—the terrible Saurians—of the Mesozoic age, the noblest of the Tanninim of old. These creatures constitute numerous genera and species, some of gigantic size, others comparatively small;—some harmless browsers on plants, others terrible renders of living flesh; but all remarkable for presenting a higher type of reptile organization than any now existing, and approaching in some respects to the birds and in others to the mammalia. ”

“ The river-plain deposits of the Age of Mammals on the other hand, are still quite extensive, especially those of its later epochs, and afford a fairly complete record in some parts of the continent of the upland fauna of those regions.
Occurrence of Dinosaur Bones. Dinosaur bones are found mostly in the great delta formations, and since those were accumulated chiefly in the early stages of great continental elevations, it follows that our acquaintance with Dinosaurs is mostly limited to those living at certain epochs during the Age of Reptiles. ”

“ The first of the armored plant-eating dinosaurs, Stegosaurus, inhabited the dry plains. There were also some smaller, kangaroo-size plant-eaters that were two-footed.
A wide variety of dinosaur fossils has been found in the rocks of the Cretaceous Period, the last of the Mesozoic Era. The huge swamp dwellers still thrived. The flesh-eaters had evolved much larger types and included 40-foot Tyrannosaurus, the largest that ever lived. All the flesh-eaters walked on their hind legs as did their predecessors of the Jurassic and Triassic Periods. ”

“ In traveling through the West, when once one has grasped the idea of continental oscillation, or submergence and emergence of the land, of the sequence of the marine and fresh-water deposits in laying down these pages of earth-history, he will know exactly where to look for this wonderful layer-bed of the giant dinosaurs; he will find that, owing to the uplift of various mountain-ranges, it outcrops along the entire eastern face of the Rockies, around the Black Hills, and in all parts of the Laramie Plains ”

“ The immense interval of time that preceded, and the no less vast stretch of time that separated them, is represented in the record of Dinosaur history by a multitude of tracks and a few imperfect skeletons assigned to the close of the Triassic period, and by a few fragments from formations which may be [24] intermediate in age between the Jurassic-Comanchic and the late Cretacic. Consequently we cannot expect to trace among the Dinosaurs, the gradual evolution of different races, as we can do among the quadrupeds of the Age of Mammals. ”

“ Some 60 million years have passed since the dinosaurs ruled the world. In that time mountains have risen, wasted away, and risen again. Glaciers have come and gone. Many species of plants and animals evolved and passed on to extinction. Every life form meets the test—adapt or die. That test is as real to the dusty lizard basking on the quarry face as it was to the dinosaurs whose bones you came to see. ”

“ In Dinosaur National Monument, the positions in which partial skeletons of the dinosaurs lie suggest that they decomposed on a sandbar. The bones on the underside of a skeleton are often arranged as they were when the animal was alive, while those on the upper or exposed side may be scattered. Such scattering would be expected as the ligaments and muscles holding the bones together decomposed; stream currents and scavengers could then disperse them. Stream currents are suggested by the position of the long, flexible tails and 21 necks of the large plant feeders. ”

“ Most great discoveries are due rather to a state of mind, if I may use such an expression, than to accident. The discovery of the immense dinosaur deposits in the Rocky Mountains in March, 1877, may truthfully be called great, for nothing in paleontology has equalled it, and that it was made by three observers simultaneously can not be called purely an accident. ”

“ Remains of Dinosaurs have been found in all the continents, but chiefly in Europe and North America. Explorations in other parts of the world have not as yet been sufficient to show whether or not each continent developed especial kinds peculiar to it, nor to afford any reliable evidence as to whether the relations of the continents were different during the Mesozoic. ”

“ We are thus fairly entitled to say that we have at least one species of animal now living which, occasionally at any rate, equals in size the very biggest and most colossal form known inferentially to geological science. Indeed when we consider the extraordinary compactness and rotundity of the modern cetaceans, as compared with the tall limbs and straggling skeleton of the huge Jurassic deinosaurs, I am inclined to believe that the tonnage of a decent modern rorqual must positively exceed that of the gigantic Atlantosaurus, the great lizard of the west, in propria persona. ”

“ Each rock formation, he knows by precept and experience, carries its own peculiar fauna, its animals are different from those of the formation above and from those in the formation below. Days and weeks he may spend in fruitless search following along the outcrop of the formation, through rugged badlands, along steep cañon walls, around isolated points or buttes, without finding more than a few fragments, but spurred on by vivid interest and the rainbow prospect of some new or rare find. ”

“ Slowly the land fell further, the sea spread out vast arms of warm water; plants and animals increased. By the Jurassic Period there was marsh again from Norway to Africa and the huge dinosaurs became the masters of the world, living on the islands and peninsulas in the midst of that shallow tropical sea. ”

“ Actually the dinosaurs show as much diversity in size, body form, and habits as any group of reptiles. The smallest dinosaur walked on its 2 hind legs like a chicken 4 and was about the same size. The largest walked on all 4 legs, was about 80 feet long, and weighed 30 to 40 tons. As examples of variety in body form there are the two-footed, flesh-eating Antrodemus, the armored Stegosaurus, the turtle-like Ankylosaurus, the horned Triceratops, the huge Apatosaurus, the two-footed vegetarian Camptosaurus, and the great variety of head forms in the aquatic hadrosaurs. ”