The masters of the ocean in Eocene times, whose skeletons are found in many parts of the world, America included.
“Even the body was only about seven feet thick,” the scientist replied. “With those sharp teeth,” he stopped and picked one from the ground, “yoke-shaped, as you see; with powerful paddles like those of a fur seal and with that tremendous tail, Zeuglodon must have been able to get around pretty lively.”
“Mammal, of course?”
“Certainly.”
“How about its hind feet, then?” asked the boy. “I know the whales have lost theirs; did their great-great-great-grandfather who left his bones here have any hind legs?”
“He did,” said the scientist, “but they were rudimentary and he kept them tucked away under his skin. Some skeletons show them plainly. In the still earlier form, Prozeuglodon, these rudimentary forms are a little more distinct.”
“Why do you suppose the Zeuglodons died out?” queried the lad.
“Hard to say,” his uncle replied; “possibly because they had too much tail for the head. So big a tail needed a lot of feeding and so small a head made it necessary for him to dine off small fish. He may have dived deep for squid, the way whales do, but, even so, the Zeuglodons seem to have been driven out by the fossil sharks.”
“Were they bigger than modern sharks?”
“They were,” answered his uncle dryly.