“On this one, sir,” the younger paleontologist answered, “in the estuarine deposit, not in the Birket-el-Qurun level. That was why I thought immediately it must be Eosiren. There’s not much chance of finding Eotherium as high as this level, is there?”
“Very little, I should say; almost none,” was the reply.
“Is there such an awful lot of difference, Uncle George?” the boy asked. “That is, between this level and the one underneath. I know, of course, the under one is the oldest, but are the fossils so different?”
“Very different, my boy,” was the reply. “They would have to be, for almost a million years passed between the deposits of this level and that. The stratum of which Antoine is speaking, just above the level of Birket-el-Qurun, is a marine limestone. This level is estuarine, that is to say, it is a deposit of material brought down by the great river that flowed through this valley millions of years ago, and like most estuarine deposits, the fossils found in this stratum are of the land as well as of the sea.
“You can understand, Perry, that in a true marine or sea deposit you wouldn’t find land animals. It would be as foolish to look for land animals in a marine deposit as it would be to go dredging in the middle of the North Atlantic now for the bones of a modern rhinoceros, or to scour the surface of the western prairies in the hope of finding a modern whale left high and dry.”
“So mine isn’t one of the oldest,” said Perry, disappointed. “I’d been hoping I’d found something that nobody had ever seen before.”
“You’re greedy,” his uncle said, smiling; “many an old fossil-hunter has worked for years before finding a specimen of a species new to science, and yet you expect to kick one up on the very first day.”
“I don’t know that I really expected to, Uncle George,” the lad replied, “but I would like to collar a new one sometime.”
“You probably will, and meantime, in the morning we’ll hustle over to the place of your discovery and find out what it is that you’ve really got.”
“I hope it’s the one you want—the Eotherium!”