_Courtesy of American Museum of Natural History_. OPENING (REAR TENT) TO MOROPUS QUARRY.] [Illustration: _Courtesy of American Museum of Natural History_. INSIDE THE MOROPUS QUARRY, AGATE, NEB. Museum expert uncovering bones of a Chalicothere, a strange creature with the teeth of a rhinoceros and clawed feet, twisted like those of an ant-eater.] “Oh, Uncle George, how big?” “Well, I found a Brontornis, or Thunder Bird, with leg bones bigger than those of an ox, standing about eleven feet high. The drumstick was thirty inches long! That would be a bird to serve whole for a Christmas Dinner instead of a fourteen-pound turkey!” Perry looked thoughtful. “I’ve got a pretty good appetite,” he said, “but I think a drumstick nearly a yard long would satisfy me!” “Even that wasn’t the strangest of my finds in Patagonia along the bird line,” his uncle continued. “Together with one of the university men I found a fairly good specimen of that queerest of fierce birds, the Phororhacus. Imagine, Perry, a bird seven feet high, with a head as big as that of a horse, and a beak ten times as big and powerful as that of an eagle. Conceive of that head and beak poised on a heavy and densely muscled neck that could strike like a thunderbolt, and I think you would agree that a blow from that ornithological pick-ax would be a good thing to dodge! In addition, you must present to yourself the idea of legs something like those of an ostrich, but more powerful and heavier, and those bore sharp tearing claws. Decidedly the Phororhacus was a bird to let strictly alone. It is hard to understand why a creature so well equipped with beak and claw perished from the earth, leaving no descendant to carry on the race.” “None of those giant birds flew, did they, Uncle George?” “No,” was the reply, “they were all too big for flight. About twenty feet span of wing or fifty to sixty pounds in weight seems to be Nature’s limit to the size of anything that flies.” “That’s the size of the Pteranodon.” “Exactly,” the professor answered, “and he was the largest of the flying reptiles. Now a bird as heavy as Phororhacus or the elephant-footed Moa would have needed a sixty-foot spread of wing. The giant birds were all flightless and they all flourished in islands and isolated places where they had few enemies. Thus, Perry, the ostriches come from Australia, the Moas from New Zealand, the Aepyornis from Madagascar and the Phororhacus from Tierra del Fuego and from South America in the period when it was isolated from the North American continent. Now in Tasmania, which is close to Australia, it happened that two carnivorous animals developed, the Tasmanian Wolf and the Tasmanian Devil. As a result, in Tasmania there are no flightless birds. When carnivores are around, the only place of safety for a bird is in the air, and since there is a limit to flight, all the successful breeds of birds are small.”