WHEN THE WORLD WAS YOUNG 191
the reptiles had mostly died out) were a good deal less numerous than the creatures who had gone before them. But this may be partly accounted for by the fact that their bodies, being lighter, would more easily float on the surface of lakes and rivers, and would be eaten by fishes, or decomposed by the air, instead of being sealed up in mud, like those of larger and heavier animals.
The very earliest kind of bird that has so far been found at all—it was in a Bavarian rock of late limestone, and is known as the Archaeopteryx—resembles, in many respects, the family of reptiles. It has, to be sure, a long jointed tail, and teeth in its jaws, and other features in common with them; but then it possesses feathers, even on its tail, and the brain of a bird. Teeth were not at all uncommon in the jaws of these early birds, and the long-billed, fish-eating, Hesperornis, of North America, had a whole set that grew afresh when the old ones fell away. The Hesperornis was between five and six feet high, and is found in the chalk rocks. It was a famous diver, and had wings of a sort; but whatever use they may have been on land, they certainly could have been of none either in air or water.
In New Zealand there existed, until comparatively lately, several ' running' birds, of the kind of which the ostrich, the cassowary and the emu are the last specimens surviving in the world. The most celebrated of these is the Moa, whose bones are found only along the banks of streams at present flowing, showing that the surface of the land has not changed since they were buried there. The Moa could not have been less than fourteen feet, as its leg bone is nearly three times as long as that of a man. Some of the tribe were slight and swift, others like the Dinornis Elephantopus, shorter and stronger. The wing bones of all were so small as to be hardly noticeable, and their bills were invariably short. Whether they could sing or not we do not know—probably not. In some cases a few