Page:Popular Science Monthly Volume 66.djvu/146

142 In 1818 the first fossil skeleton found in the valley was discovered at New Windsor, Conn., and later, just before the civil war, another was brought to light at Springfield, Mass. These, while fragmentary, were recognized to be reptilian in character, and when the latter specimen came to light it at once cast a grave doubt upon the correctness of the accepted interpretations. Hitchcock himself speaks of these remains as being 'those of fair representatives of the creatures which made the tracks.'

It was not until nearly the last decade of the nineteenth century that further excavations at New Windsor, which resulted in the finding of two more specimens, enabled Professor Marsh, of Yale University, to restore the creature and to give us an adequate knowledge of its organization and affinities and thus to furnish the first true key to the correct interpretation of the footprints. Further discoveries abroad, but more especially in our own great west, have given us a very complete knowledge of the magnificent race of reptiles to which the Connecticut Valley forms belong.

During the Mesozoic age, comparable to the medieval times in human history, reptiles were the dominant forms; they occupied the places in the economy of nature to-day taken by the birds and beasts, both animal and plant feeding, as well as by the whales and other denizens of the air, earth and sea; but among the great reptilian assemblage none were more varied in size, aspect and habits than the dinosaurs or terrible lizards, at that time the peers of the animal realm. These creatures are first known from the rocks of the Triassic, the earliest of the three periods into which the Mesozoic age is divided, reaching their millennium as a race during the close of the second or Jurassic period, at which time they attained their greatest profusion in numbers and their highest development in point of size. In the strata formed toward the close of the Cretaceous, or final period, the dinosaurs reach their maximum of specialization, developing forms among the most weird, grotesque, as well as the most terrifying, the world has ever known. This marks the decadence of the race, the prelude to its extinction, for in the immediately overlying rocks of the Tertiary period not the least vestige of a dinosaur has been found.

At least three great orders of Dinosauria are recognized, of which two, embracing the land forms, were represented in the footprint fauna, while of the third, gigantic quadrupeds, whose vast bulk has won for them the name of Cetiosauria or whale lizards, plant feeding and semi, if not wholly, aquatic in their habits, there, is not a trace.

The remaining orders were sharply differentiated in their habits of feeding, the one being carnivorous, the other herbivorous, in diet; and while the more primitive members of both orders were quite similar, such is the influence of habit upon a race that their evolution