“Some day, perhaps, Perry, you may be lucky enough to find one still earlier! Think of a Triassic reptile heralding a bird! That would be a triumph, for there must have been some small leaping dinosaur which gave signs of bird-like development. Just think, Perry, if you should be the one to make the grand discovery!” “It would be great,” cried the boy. “That’s the excitement of paleontology,” went on the other, enthusiastically. “You’ve read of the gold-fever, and how men will spend their lives alone in the mountains, hunting for nuggets. Then, when they find them, the gold is just like all the rest of the gold in the world. But when we find something new, it’s something that no human eye has ever seen before, it’s the gateway into a new world. Any day, if we were on an expedition among Triassic rocks, we might find the bird that lived before the Archæopteryx and learn for the first time exactly how the birds first came to be.” “There aren’t any birds living to-day that are like those old primitive ones, are there, Antoine?” “Not really alike,” the other answered, “because those early birds were still half reptiles. For example, the Archæopteryx had a long tail like a lizard, with a feather on each side of each joint. Then, too, he had claws on the joints of his wings. Now, there is still one bird living that has claws on the end of its wings when young, and climbs around the trees with them before it learns to fly. That’s the—” “Hold on!” cried Perry. “I’ll tell you the name. Wait a bit!” He thought hard. “It’s the—the—Hoactzin, isn’t it?” “Right, right,” said Antoine, “you have read your books well. The first birds were not highly developed, and probably they were not as good flyers as the flying lizards. Most likely they only took short flights. Still, the future was theirs, for they were built upon a better plan.” “Because of the wing-flapping?” “Yes, for one reason. But the pterodactyls might have developed that. Indeed, some of the little ones may have been able to flap. It was the cold that first gave the birds their real start.” “The Ice Age?” “Not the one you mean, Perry, but the second Ice Age, at the end of the Age of Chalk. It makes the geological history of the world a great deal easier to remember, if you divide it into the three great Ages of Ice. The first came at the end of the Coal-Forest time or the Carboniferous Period and closed the Empire of Fishes and Amphibians; the Second Age of Ice came at the end of the Age of Chalk, or the Cretaceous Period, and it closed the Empire of Reptiles; the Third Ice Age came at the end of the Pliocene Period and it closed the Empire of the Beasts. As the Ice-sheet of the Glacial Epoch slowly drew back toward the North Pole, Man took his place as the leader of Life.” The boy looked up quickly. “That’s a dandy division, Antoine,” he said; “it’s heaps easier to remember that way. And you say it was the Second Ice Age that shoved the birds ahead?”