The Outline of History: Being a Plain History of Life and Mankind

by H. G. Wells

The earliest known reptiles were beasts with great bellies and not very powerful legs, very like their kindred amphibia, wallowing as the crocodile wallows to this day; but in the Mesozoic they soon began to stand up and go stoutly on all fours, and several great sections of them began to balance themselves on tail and hind legs, rather as the kangaroos do now, in order to release the fore limbs for grasping food. The bones of one notable division of reptiles which retained a quadrupedal habit, a division of which many remains have been found in South African and Russian Early Mesozoic deposits, display a number of characters which approach those of the mammalian skeleton, and because of this resemblance to the mammals (beasts) this division is called the Theriomorpha (beastlike). Another division was the crocodile branch, and another developed towards the tortoises and turtles. The Plesiosaurs and Ichthyosaurs were two groups which have left no living representatives; they 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 in East Africa, was still more colossal. It measured well over a hundred feet! These greater monsters had legs, and they are usually figured as standing up on them; but it is very doubtful if they could have supported their weight in this way, out of water. Buoyed up by water or mud, they may have got along. Another noteworthy type we have figured is the Triceratops. There were also a number of great flesh-eaters who preyed upon these herbivores. Of these, Tyrannosaurus seems almost the last word in “frightfulness” among living things. Some species of this genus measured forty feet from snout to tail. Apparently it carried this vast body kangaroo fashion on its tail and hind legs. Probably it reared itself up. Some authorities even suppose that it leapt through the air. If so, it possessed muscles of a quite miraculous quality. A leaping elephant would be a far less astounding idea. Much more probably it waded half submerged in pursuit of the herbivorous river saurians.

§ 2

One special development of the dinosaurian type of reptile was a light, hopping, climbing group of creatures which developed a bat-like web between the fifth finger and the side of the body, which was used in gliding from tree to tree after the fashion of the flying squirrels. These bat-lizards were the Pterodactyls. They are often described as flying reptiles, and pictures 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 the Mesozoic jungles. But bird-like though they were, they were not birds nor the ancestors of birds. The structure of their wings was altogether different from that of birds. The structure of their wings was that of a hand with one long finger and a web; the wing of a bird is like an arm with feathers projecting from its hind edge. And these Pterodactyls had no feathers.

§ 3

Far less prevalent at this time were certain other truly birdlike creatures, of which the earlier sorts also hopped and clambered and the later sorts skimmed and flew. These were at first—by all the standards of classification—Reptiles. They developed into true birds as they developed wings and as their reptilian scales became long and complicated, fronds rather than scales, and so at last, by much spreading and splitting, feathers. Feathers 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 with it—and spread to the north and south polewards beyond the temperature limits set to the true reptiles. The earliest birds seem to have been carnivorous divers and water birds. To this day some of the most primitive bird forms are found among the sea birds of the Arctic and Antarctic seas, and it is among these sea birds that zoologists still find lingering traces of teeth, which have otherwise vanished completely from the beak of the bird.

The earliest known bird (the Archæopteryx) had no beak; it had a row of teeth in a jaw like a reptile’s. It had three claws at the forward corner of its wing. Its tail too was peculiar. All modern birds have their tail feathers set in a short compact bony rump; the Archæopteryx had a long bony tail with a row of feathers along each side.