§ 3. The First Birds. § 4. An Age of Hardship and D

compressed and mummified,[14] are now coal, prevailed over most of the world. There were some cold intervals, it is true; but they did not last long enough to destroy th

that were distinctly land plants growing on soil above the water level. The lower levels of the Mesozoic land were no doubt covered by great fern brakes and shrubby bush and a kind of jungle growth of trees. But there existed as yet no grass, no small flowering plants, no turf nor greensward. Probably the Mesozoic was not an age of very brightly coloured vegeta

of our time. He must think of low-growing evergreens. The mountains were still as bare and lifeless as ever. The only colour effe

ime of the Upper Pal?ozoic; but the fundamental difference between reptiles and amphibia which matters in this history is that the amphibian must go back to the water to lay its eggs, and that in the early stages of its life it must live in and under water. The reptile, on the other hand, has cut out all the tadpole stages from its life cycle,

lligence with no knowledge of the future had come to earth and studied life during the early Pal?ozoic age, he might very reasonably have concluded that life was absolutely confined to the water, and that it could never spread over the land. It found a way. In the Later Pal?ozoic Period that visitant might have been equally sure that life could not go beyond the edge of a swamp. The Mesozoic Per

hey were huge reptiles returning to a whale-like life in the sea. Pliosaurus, one of the largest plesiosaurs, measured thirty feet from snout to tail tip-of which half was neck. The Mosasaurs were a third group of great porpoise-like marine lizards. But the largest and most diversified group of these Mesozoic reptiles was the group we have spoken of as kangaroo-like, the Dinosaurs, many of which attained enormous proportions. In bigness these greater Dinosaurs have never been exceeded, although the sea can still show in the whales creatures as great. Some of these, and the largest among them, were herbivorous animals; they browsed on the rushy vegetation and among the ferns and bushes, or they stood up and grasped trees with their fore legs while they devoured the foliage. Among the browsers, for example, were the Diplodocus carnegii, which measured eighty=four feet in length, and the Atlantosaurus. The Gigantosaurus, disinterred by a German expedition in 1912 from rocks

es are drawn of Mesozoic scenery in which they are seen soaring and swooping about. But their breastbone has no keel such as the breastbone of a bird has for the attachment of muscles strong enough for long-sustained flying. They must have flitted about like bats. They must have had a grotesque resemblance to heraldic dragons, and they played the part of bat-like birds in

are the distinctive covering of birds, and they give a power of resisting heat and cold far greater than that of any other integumentary covering except perhaps the thickest fur. At a very early stage this novel covering of feathers, this new heatproof contrivance that life had chanced upon, enabled many species of birds to invade a province for which the pterodactyl was ill equipped. They took to sea fishing-if indeed they did not begin wi

hree claws at the forward corner of its wing. Its tail too was peculiar. All modern birds have their tail feather

me the break represents; many pages may be missing here, pages that may represent some great cataclysmal climatic change. When next we find abundant traces of the land plants and the land animals of the earth, this great multitude of reptile species had gone. For the most part they have left no descendants. They have been "wiped out." The pterodactyls have gone absolutely; of the plesiosaurs and ichthyosaurs none is alive; the mosasaurs have gone; of the lizards a few remain, the

ith the close of a vast period of equable warm conditions and the onset of a new austerer age, in which the winters were bitterer and the summers brief but hot. The Mesozoic life, animal and ve

s a vast multitude and variety of these coiled shells; there are hundreds of species, and towards the end of the Mesozoic period they increased in diversity and produced exaggerated types. When the record resumes, these too have gone. So far as the reptiles are concerned, people may perhaps be inclined to argue that they were exterminated because the Mammals that replaced them competed with them, and were more fitted to survive; but nothing of the sort can be true of th

petition. To judge by the Record of the Rocks as we know it to-day, there is much more reason for believing that first the reptiles in some inexplicable way perished, and

mals in the Me

ater Mesozoic a number of small jaw-bones are found, entirely mammalian in character. But there is not a scrap, not a bone, to suggest that there lived any Mesozoic Mammal which could look a dinosaur in the face. The Mesozoic mammals or mammal-like reptiles-for we do not know clearly which they were-seem to have been all obscure little beasts of the size of mice and rats, more like a down-trodden order of reptiles than a distinct class; probably they still laid eggs and were developing onl

rly mammals. Leading lives upon the margin of existence, away from the marshes and the warmth, they developed an outer covering only second in its warmth-holding (or heat-resisting) powe

to an equable climate and to shallow and swampy regions. But in the case of their Cainozoic successors, both hair and feathers gave a power of

Lower Pal?ozoic Period wa

zoic Period was confined to warm wat

know it was confined to water and fairly low-

f life beyond the limits prevailing in that period; and when ages of extreme conditions

's geographical range is from pole to pole, he goes under the water in submarines, he sounds the cold, lifeless darkness of the deepest seas, he burrows into virgin levels of the rocks, and in thought and knowledge he pierces to the centre of the earth and reaches out to the uttermost star. Yet in all the relics of the Mesozoic time we find no certain memorials of his ance