Page:Popular Science Monthly Volume 3.djvu/446

432 joints of the toes, like the tracks of the ostrich, turkey, and our common domestic fowls. The feet are invariably trifid, and the number of phalanges corresponds perfectly to that observed in the toes of all living birds, viz., three in the inner, four in the middle, and five in the outer toe, including the claws. The inner phalanges are united to the lower leg-bone abreast of each other, a little back of the middle one, and thus the imprint may also show rounded impressions made by the heel, which have been mistaken for phalangeal markings. This thick-toed group invariably took very long steps, corresponding well with the ordinary gait of their living representatives. One of them, with a foot less than three inches long, had a stride of 25 inches, showing a general structure like that of the waders. Moreover, the entire width of the track-way is scarcely greater than that of each individual foot, indicating a very narrow body, stilted high upon long legs. The smallest of this group may be compared with the living snipe; the largest, having a foot 18 inches long, must have equalled in size the largest of the recently-extinct birds of New Zealand, the Deinomis giganteus, 10 feet high. The principal genus is the Brontozoum (the animal giant); and of the thousands of examples of those yet exhumed, not one shows any features in addition to those described, neither a fourth toe, the trace of a front-foot, nor any indication of a tail. Hence, though suggestions as to their reptilian character are abundant, we shall wait for proof that some distinct reptilian feature is joined to the ornithic, before allowing that the Brontozoum, or Grallator, were not true birds.

But the next group gives evidences, neither scanty nor ambiguous, to prove the existence of a large number of "ornithic reptiles," or "reptilian birds." This order is now entirely extinct, and was first made known to the world by E. Hitchcock's description of the "ornithoid lizards, or batrachians." He saw that some of the characters were ornithic, and that others were reptilian, so that he was compelled, though reluctantly, to refer them to an altogether new group of life. Since this reference, an abundance of discoveries has confirmed these views; and the name of Herpetoids has been suggested for them by Prof. Dana.

The general form of the animal was kangaroo-like, with enormous hind-limbs, a prominent tail, and small front extremities, which were rarely if ever brought to the ground so as to make an impression. The animal may often have walked only upon the trifid hind-feet, showing neither the front-feet, the long shin-bones, nor the caudal appendage. We have seen such rows of trifid impressions, 25 or 30 in number, which might hastily be referred to the feet of birds. But, though the general appearance is ornithic, and the number of phalanges agrees with those of birds, the thirty-first impression reveals a kangaroo-form on all-fours—two small five-toed feet in front, two trifid impressions of larger dimensions at the end of a long heel-mark behind, followed