The footprints of a small reptile had been observed on the sandstone of a near Elgin, which most probably belongs to the old red sandstone measures. In 1851 it was discovered that they were produced by a little reptile (telerpeton Elginense). whose remains were there found. And more recently, prof. Huxley has referred a different set of impressions to the remarkable fish-like reptile, stagonolepis, which he describes.
The coal measures of our own country and of Germany have disclosed the footprints of different reptiles.
The new red sandstone strata abound in footprints. It was the permian or lower division of this series that supplied, in 1828, the impressions which gave the first indi cation of animal life from such evidences to the mind of Dr. Duncan—a man who deserves to be remembered less for his works in natural history, important though they were, than for his eminent services to his country as time founder of savings-banks. The tracks he described occur on the layers of unctuous clay which separate the beds of sandstone in the quarries at Corneockle, Dumfriesshire; they frequently are and delicate, as at the moment when they 4ere impressed, and are repeated bed aftoii bed on the fresh tablets as they were prepared for their reception. From their number' and direction, they seem to be the tracks of animals passing together across a tide receded estuary, to some frequented.ground periodically sought for food or pleasure. No animal remains whatever have been found associated with • theni, they seem, how ever, to belong to forms of tortoise. The pad of the foot was soft and smooth; the light
impressions of the fore-foot were nearly obliterated by the hind-foot, which was tut. Dished with four claws. Sir William Jardine, on whose property the Corneockle quarries are, has made these tracks the subject of a valuable and elaborate monograph.
In the triassic rocks the well-known foot tracks of the labyrintliodoy (q.v.) occur.
The earliest evidence of the existence of birds are the traces of their feet in the argillaceous sandstones of which are now known to be of the lower oolitic age. The structure of the tridactyle feet which produced these impressions exhibits the regular progression in the number of the toe-joints from the innermost to the outer most toe peculiar to birds, and they must be taken as evidencing the occurrence thus early of the class, although a considerable interval elapses before the first true fossil of a bird occurs; namely, the remarkable long-tailed bird from the upper oolite rocks of Solenhofen, recently described by prof. Owen. Immense tridaetyle footprints have been known for many years in rocks of \veal den age in the s.e. of England. At first they were supposed to be birds; but a more careful examination has shown them to belong to reptiles; and the discovery in the same strata of the perfect foot of a young iguanodon, measuring 21 in. in length, and furnished with three toes, which would form it print precisely similar to the tracks so long known, shows them to have been certainly produced by the iguanodon (q.v.).