GREAT DINOSAURS

Evening Post, Volume CXVIII, Issue 93, 17 October 1934, Page 18

GREAT DINOSAURS

ANCIENT ARISTOCRATS

WHEN THEY ROAMED THE WORLD

VICTIMS OF CLIMATE

The horned dinosaurs had the largest! skulls of all' land animals. The biggest known fossil skull of a horned dinosaur is only ii little smaller than the skulls of the largest whales of the [ present time. Professor K. S. Lull, of [ Yale University, has published au inI tcresting now volume on this rcmarki able type of dinosaurs in the "Memoirs lof the Peabody Museum of Natural 1 History," says a writer in the "Manchester Guardian." The dinosaurs camo into existence about 175,000,000 years ago, and dominated the earth for about 100,000,000 years. Their latest and finest representatives were the horned dinosaurs, but theso aristocratic products of a long period of evolution died out about 75,000,000 years ago. They wore probably tho most intelligent of their order, but their brains weighed only about half a pound. The largest horned dinosaurs weighed about ten tons and had skulls about eight feet long. A man's brain weighs about threo pounds and his body about 150 pounds. Hence tho ratio of brain-weight to body-weight in the horned dinosaur is about one to forty thousand, and in a man about one to fifty. The horned dinosaur was the summit of 100,000,000 years of evolution along one line of development. Those parts of the brain of the horned dinosaur concerned with the senses of smell ami sight were relatively well developed. Also the pituitary gland was relatively of enormous size. The imrhense size of the dinosaurs was no doubt connected with tho special development of this gland, which is concerned with growth. Tho auditory tracts in_ the brain were undeveloped, so the animal had a poor sense of hearing. Lull considers that this is not very important because its enemies were also huge and clumsy animals that must have made a great crushing and flopping when they approached. If the dangerous rivals could not attack without making a loud noise a delicate sense of hearing was not of a crucial advantage. THEIR NECK SHIELD. Tho most remarkable feature of the skeleton is tho enormous neck shield. This grows from tho back of the skull over the back of the neck. Its purpose was, apparently, to protect tho neck, which was peculiarly vulnerable. The skull was carried on a sort of universal joint to allow sharp and powerful twisting movement and the flexibility was obtained at the expenso of strength along certain directions. Heneo the animal could easily be incapacitated by a suitable external blow. By covering the neck with an immense bone shield tho danger of destruction from this form of attack was reduced. Besides the unique ueck shield the skull bore an armoury of horns. The horns are believed to have been used for offensive action because the fossils of many dinosaurs exhibit holes presumably duo to punctures made by the horns of charging enemies. Lull believes tho animal chargod head-on. This is curious because the eyes wero so placed that it could not see directly in front, but only to its sides, like a sperm whale. Specimens with broken horns aro often found. In some cases the horns appear to have been broken in combat. HOW THEY FED. Unlike soino other giaut contemporaries, tho horned dinosaur was a vegetarian, and its pugnacity does not seem to have been curtailed by its diet. It had an immense beak, backed by many hundreds of teeth arranged in about thirty rows. Tlio general structure of the mouth was as efficient as that of a modern rhinoceros. The teeth had enamel of poor quality and were less durable than the teeth of modern mammals. Nevertheless, the almost endless succession of teeth gave the animal an advantago over a modern mammal with superior but permanent teeth which, when onco worn out could not be replaced. The teeth of the horned dinosaur, unlike- those of the modern mammal, did not set a limit to its expectation of life. Tho mouth was quite unsuited to tho rending of prey. Tho jaws were operated in a vertical or chopping movement, without any fore-and-aft or sideways motion, lne upper and lower teeth did not meet and lie against each other, but slid past, tho outer sides of the upper :ccth sliding against the inner sides of the lower teeth, as in a shearing machine. . The ball-and-socket bearing of the skull allowed the head to bo swivelled in an exceptional degree. The animal is supposed to have twisted its neck until it could seize plant stems firmly with its beak. It then twisted its neck back violently, tearing away or snapping the stem. The bow-legged stance of the forelegs provided a iirm support for such an operation by the head. While the horned dinosaur was vegetarian, the contemporary tyrannossaurs were carnivorous. Those very large animals could have dislocated the ball-and-sockot joint iv the horned dinosaur's neck by treading on it or biting it if it had not been protected by the huge bone shield. FOSSIL REMAINS. The fossils of horned dinosaurs were first found in Montana in 1855. Since then many specimens have been found in the central districts of tho United States, in Canada, and in Mongolia. The Oanadaians have mado interesting explorations in rivers such as the Red Deer, whoso bods contain many fossil bones. They built large scows bearing pitched tents for themselves and their implements, and drifted on a four-mile-an-hour current through canyons and tributary valleys collecting fossils from tho banks. I In 1922 Andrews and Granger found I the fossils of an ancestor of tho horned dinosaurs in Mongolia. These forerunners were much smaller and had neck shields but no horns. Besides the bones of adults, they found nests of eggs, tho first nests of extinct - reptiles to bo discovered. Some' of the eggs contained fossilised embryos. Tho monsters lived in a vast swamp drained by interlacing streams whose i courses were continually changing. The vegotation was abundant and essentially modern; flowcr-boaring plants, ferns, sequoia, poplars, beeches, elms, sycamores, maples, and oaks. Flowervisiting insects wero alroady in existence. Tho profusion of plant lifo was sufficient to supply the material for < extensivo bods of coal. The climate was probably warm and equable, but ■ not necessarily tropical. The extinction of the dinosaurs was probably due i to the rising of the land, which converted huge swamps into what is now . a vast semi-arid plateau. Tho horned dinosaurs wore better i adapted to life on land than in waier. Their feet were fairly compact and could bo effective only on fairly firm land. They probably visited waterholes, but did not live in water. Their i manner of life was rather similar to i that of the modern browsing rhino- i ceros. It is thought that thry retired < to dry upland regions to lay their t'ggs. < Indeed, they were probably descended ( from small animals accustomed to a ;

dry upland habitat, and not from the giant amphibious and aquatic dinosaurs of earlier epochs. The horned dinosaurs returned to tho homes of their dry-landed ancestors to breed, and went down to the coasts to live on tho profuse vegetation near water when they had become adult. This behaviour may be tho explanation of the rarity of fossils ol" very young animals. The very young and the adults did not live in tho same districts, and the adults died in places where their remains had a better chance of preservation. . BEAIN AND SURVIVAL. j Such is tho rough story of a race of animals unknown until eighty years ago, whose relatives nourished for a hundred million years, and who did so themselves for a considerable part of that period. They departed from life during an almost universal catastrophe to reptilian life, which occurred about seventy-five million years ago and which was largely due to changes in tho earth's crust that produced climates inimical to reptiles. Tho staying power, in suitable environments, of relative brainlessness is unedifying. It is true that the potentially brainier animals survived but the attribution of their survival to their brains, though comforting, may not bo true. The survival and development of animals with superior brains may have been due much more to the accidents of geological change than to the natural selection of the more intelligent. . Other things being equal, the intelligent have a great advantage over thp unintelligent, but if other things are not equal intelligence may have to retire in inconspicuous forms to inconspicuous places, and there wait for long periods until the thick-skinned and thick-skulled lords of contemporary creation arc overwhelmed by natural changes to which they are unable to adapt themselves. When these monsters, proof even against brains, are gone, their humbler but brainier successors have the opportunity to develop higher forms of life.