THE FOSSIL RHINOCEROSES.
Although the species of Rhinoceroses living at the present time are but few, the researches of palæontologists show us that in past time the number of species was considerable, and that they were not, as now, confined to the warmer parts of the Old World, but were distributed over a large portion of Northern Asia and Europe.
The first representative of the Rhinoceros family is the Orthocynodon, an animal with large upright canines, discovered in the Upper Eocene strata of the United States. The fossil Rhinoceroses properly so called are first found in the Miocene, and are divided into four groups. The first group is characterised by the nostrils being separated by a bony partition, and in the adult animal the incisor teeth are lost: the second is distinguished by the absence of a bony partition between the nostrils, and the incisor teeth are of a medium size: in the third there is no partition, but the incisors are large; and in the fourth it is imperfectly developed.
An example of the first group, and probably the best known form of all the extinct Rhinoceroses, is Rhinoceros tichorhinus, or the Woolly Rhinoceros. Like that of the Mammoth, with which animal it was evidently associated, its entire body was covered with hair and wool, the skin had no folds, and its nose carried two horns, the anterior of which was of remarkable size, and characteristic of the group to which it belongs; the nostrils were separated by a complete bony partition. The Woolly Rhinoceros has been discovered under similar circumstances to that of the Mammoth, having been found embedded in ice in the northern latitudes of Asia, in the years 1771 or 1772, being some twenty years previous to that of the discovery of the first Mammoth by a fisherman named Schumachoff. According to Pallas, the discovery was made by some Yakuts, who were on a hunting expedition, and took its dimensions on the spot; it was about eleven and a half feet in length. Its body was still clothed with skin, but altogether the animal was so far decomposed that not more than the head and feet could be brought away. On the skin many short hairs still remained. The range of the Woolly Rhinoceros was undoubtedly the same as that of the Mammoth, except that it did not cross Behring Strait, and, consequently, its remains are not found in America. The remains of the Woolly Rhinoceros are found in numerous caves in association with the remains of Hyænas, having undoubtedly been a staple article of food for these animals. In England remains have been found in the caves at Creswell, Nottinghamshire; in the Brixham Cave; in Kent’s Hole, near Torquay, Devonshire; and in Wookey Hole, near Wells, Somerset, as well as in the caves of Wales and Derbyshire.
As an example of the second group, we have Rhinoceros megarhinus of the Pliocene and Pleistocene strata. This animal possessed two horns. Its remains are found in France and Italy, and in the pre-glacial forest bed of Cromer, and in the lower brick earths of the Thames valley. Rhinoceros incisivus represents the third group in Miocene times. It had no bony septum between the nostrils, the incisors are large, and there are four toes on the fore-foot. Of the fourth group the best examples are R. etruscus and R. leptorhinus. The former of these possessed two horns, and the nostrils were separated by an imperfect bony septum. Its remains are found in various Pliocene and Pleistocene deposits. The latter also possessed two horns, and its nostrils were divided by a thin and delicate bony partition, which can only be termed imperfect in comparison with the massive partition in the Woolly Rhinoceros. It is devoid of incisors. This species is found in Pleistocene deposits in Britain, France, and Italy, in caverns, and in river-beds, the most perfect remains being met with in the valley of the Thames near Ilford. These were collected by Sir Antonio Brady, and are now to be seen in the British Museum. In the figure the fragile nose septum is represented as broken.
SKULL OF FOSSIL RHINOCEROS [R. LEPTORHINUS].
The genus Aceratherium, of Kaup, is a hornless Rhinoceros, found in the same Miocene strata as the R. incisivus. Like the latter, it possesses incisors, and, not improperly, may be considered as a female of the latter species, if the horn be viewed as a sexual characteristic: first of all in the possession of the male, and afterwards transferred by descent, in the case of all the Post-Miocene Rhinoceroses, to the female.
THE EXTINCT FAMILY PALÆOTHERIDÆ.
The Palæotheridæ, or fourth family to be considered under the head of the Perissodactyla, is that which is found only in the fossil state in the Eocene strata of Europe and North America. They are allied, on the one hand, to the Horses, and on the other to the Tapirs. The type of the family, the Palæotherium, was originally discovered by Cuvier in the quarries of Montmartre, near Paris. The grinding teeth closely resemble, in the pattern of their grinding surfaces, those of the Rhinoceros. The full complement, however, of incisors and canines, as well as of grinders, is present in each jaw, namely—Incisors, 3; canines, 1; premolars, 4; molars, 3. These animals varied in size from that of a Roedeer to that of a Tapir, and were possessed of three well-developed hoof-bearing toes.