Page:Popular Science Monthly Volume 3.djvu/449

Rh kangaroo-like reptiles flourishing, in the later Mesozoic times, in all quarters of the globe. All those new forms present features clearly defining them from both birds on the one hand, and reptiles on the other, so that we are warranted in believing in the existence of genuine birds as well as of ornithic reptiles in ichniferous times.

The Triassic period was par excellence the Age of Reptiles. Besides the Ichnozoa, the museums teem with specimens of fossil bones of various types of Amphibian, Batrachian, Crocodilian, and Lacertilian forms. We should, therefore, naturally expect that a kangaroo-form of body was not indicative of marsupial structure, but rather a modification of reptilian, in the passage, if we may so speak, of the Lacertian to the Ornithic type.

Twenty-one of the Connecticut ichnites have been inferred to the ordinary type of reptiles—the Lacertians—and six to the turtles. Perhaps the number of the former should be increased at the expense of the marsupials and narrow-toed birds. The largest reptile foot is about 15 inches long, three toes in front, curved toward the line of march. It has, besides, a stout thumb, or spur, pointed inwardly. The track-ways of turtles show the trail of the tail, in addition to a pair of feet on both sides.

The group of Amphibians, chiefly batrachians, contains several of interest. Prominent among them is the Otozoum, a track discovered by Mr. Pliny Moody, the first person in the whole world who exhumed an ichnite, so far as has been determined. The animal had a foot 20 inches long, very broad, perhaps web-footed, embracing not less than a square foot of surface. In shape it resembles the Cheirotherium, only it had three fingers instead of four, with a thumb. One species has the thumb recurved, and the other shows it pointed