Fig. 296.—Thylacine, or “Tasmanian Wolf” (Thylacynus cynocephalus).—By permission of W. S. Berridge, London.
The other forms to be mentioned belong to the closely allied family of the Dasyuridæ. The “Tasmanian Devil” (Sarcophilus ursinus) is now, like the Thylacine, confined to Tasmania, but remains of it have been found in the Australian Pleistocene; it has one less premolar in each jaw, giving the formula: i 4/3, c 1/1, p 2/2, m 4/4, × 2 = 42; there is no milk-tooth. The premolars are closely crowded and the molars resemble those of the Thylacine in construction, but are broader and heavier. The skull is disproportionately large, with shorter and wider muzzle and jaws than in the Thylacine; the tail is of only moderate length and somewhat shaggy; the hallux is wanting. In size and build, the Tasmanian Devil resembles a badger and has long and heavy fossorial claws on the fore feet; the hair is rough and shaggy, black in colour with white patches. The animal has received its name from its fierce and savage disposition and is almost as destructive to sheep as the Thylacine.
The five species of Dasyurus are distributed through Tasmania, Australia and New Guinea and are called “Native Cats”; they are much smaller animals than the two preceding genera, not exceeding a domestic cat in size. As the Thylacine imitates a wolf and the Tasmanian Devil a badger, the dasyures resemble the civets. In them the dental formula is the same as in Sarcophilus, but the teeth have higher and sharper cusps. The head has a narrow, tapering muzzle and narrow ears; the body is long and the tail of moderate length. The limbs are short and slender and a small hallux is present in some of the species. The fur is grey or brown, with numerous white spots, and the tail is covered with long hair, but not bushy. The dasyures are largely arboreal and prey upon small mammals, birds and eggs.
Until the arrival of the true Carnivora from the north, their rôle was taken in South America by predaceous marsupials, which persisted as late as the presumably Pliocene beds of Monte Hermoso. Little is known of them in that stage, however, or in the older Paraná, but abundant material representing those of the Santa Cruz has been collected. Among these there was a considerable range of size and some variety of structure, and they all differed in certain respects from the modern Australian genera, differences which have led some authorities to deny the marsupial character of all these South American forms. The differences are of three kinds: (1) there are no vacuities in the bony palate; (2) the milk-dentition is less reduced, the canines and one or two premolars being changed; (3) the enamel of the teeth, in the only genus (†Borhyæna) which has been examined microscopically, resembles in its minute features that of the placentals and lacks the marsupial characters. Though by no means unimportant, these differences are altogether outweighed by the thoroughly marsupial nature of all other parts of the skeleton, and I cannot but agree with Dr. Sinclair[20] in including them in the same family with the Tasmanian Thylacine.
The genus †Prothylacynus was especially like the latter and must have had a very similar appearance, though in the restoration ([Fig. 297]) the colour-pattern is changed to one of longitudinal stripes, as more probably pertaining to so ancient and primitive a form. The humerus had the epicondylar foramen, and a large vestige of the hallux was retained, though it could not have been visible in the living animal.
A more specialized Santa Cruz genus was †Borhyæna ([Fig. 244, p. 494]), an animal of about the same length and height as †Prothylacynus and the Thylacine, but much more massive and powerful. The skull was remarkable for the small size of the brain-case and the great spread of the zygomatic arches, which gave a rounded and almost cat-like appearance to the head, as is shown in the restoration ([Fig. 244]). In this genus the upper incisors were reduced to three, a very unusual thing among the Polyprotodonta, and the humerus had lost the epicondylar foramen. †Prothylacynus and †Borhyæna were the largest of the Santa Cruz flesh-eaters and no doubt pursued the smaller and more defenceless ungulates, but were hardly sufficiently powerful to attack successfully the larger hoofed animals, which were probably well able to defend themselves.
Fig. 297.—Santa Cruz predaceous marsupial (†Prothylacynus patagonicus) and †typothere (†Interatherium robustum). Restored by C. Knight from skeletons in the museum of Princeton University.