“Of course the animals that lived on the earth in its flatter, more temperate stage now have to adapt themselves to life on high, cold elevations, or in dry, hot desert areas, or to migrate via the land-bridges to more favorable climates. Those unable to do this perished.
“For instance, take the age of reptile dominance, (the Mesozoic Era), which was in turn divided into four periods, those of dinosaurs, (the Triassic period, a rock from which I showed you, if you remember), the Jurassic period, which gave rise to flying reptiles, from which our first birds were derived; the Comanchean period, which gave rise to flowering plants and the higher insects, and the Cretaceous period, when our most primitive mammal forms evolved.
“At first the earth was peopled with dinosaurs and flying dragons, and the seas by squid-like mollusks. In those days all the earth was level, swampy, tropic and overgrown with giant tree ferns and a primitive conifer.
“As the high mountain ranges arose and deserts were made, these forms gradually gave way to flowers and hardwood forests, peopled with insects and mammals. Only the most intelligent forms survived, and the struggle itself developed a higher degree of intelligence.”
“What in tarnation were dinosaurs?” asked Long Lester.
“Oh, haven’t you ever seen pictures of them?” laughed Ace. “Picture a giant lizard, perhaps 40 feet long––”
“Here, here,” protested the old man. “I don’t bite.”
“It is perfectly true,” said Norris soberly.
“Honest Injun!” vowed Ace. “One of these fellows was a sort of cross between a crocodile and a kangaroo, what with his long hind legs that he could walk half erect on. There were some as small as eight or ten inches, too, and some so large that you wouldn’t have come to his knee. His big toe was as long as your arm.”
“And how do you know all that?” protested the old prospector feebly.