. ants, the mammals, continued the germ of life, carrying on and perfecting the pattern first laid down by the theriodonts. Thus it may be said that the theriodonts, in evolv- ing as they did, sealed their own doom. Indeed, they sealed the doom of the entire reptilian world, for they were the progeni- tors of a race that was destined to wrest the control of the land and the waters and the air from them. Yet the doom of reptilian dominance was not to come until future ages in the geologic story. The first mammals, the descendants of the theriodonts, appeared in the Triassic, some 200 million ye
. ants, the mammals, continued the germ of life, carrying on and perfecting the pattern first laid down by the theriodonts. Thus it may be said that the theriodonts, in evolv- ing as they did, sealed their own doom. Indeed, they sealed the doom of the entire reptilian world, for they were the progeni- tors of a race that was destined to wrest the control of the land and the waters and the air from them. Yet the doom of reptilian dominance was not to come until future ages in the geologic story. The first mammals, the descendants of the theriodonts, appeared in the Triassic, some 200 million years ago, but through the millions of years that constituted the Juras- sic and Cretaceous periods the descendants of these first mammals played a relatively insignificant part in the economy of life. The world still belonged to the reptiles; in fact, it was during the lush days of Jurassic and Cretaceous times that the reptiles rose to the greatest heights of their long histoiy on this sphere. Those were the days of the dinosaurs, when there were giants on the earth. 59
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Keywords: ., bookcentury1900, bookpublishernewyork, booksubjectreptilesfossil
