The Tasmanian devil (Sarcopizilus ursinus) is a short-bodied burly dasyurid with a broad muzzle, an enormous, broad and massive skull and most powerful jaws. There are strongly de veloped blades on the upper and lower molar teeth, which re semble those of such extinct placental carnivores as Oxyaena. The inner projections of the upper molar crowns are reduced and the planes of the inner surfaces of these blades now point more obliquely backward than those in the more primitive pouched mice.
In the marsupial wolf or tiger (Thylacinus) the general habitus is somewhat wolf-like, except that the feet are shorter and the hinder part of the body gradually tapers into the tail. Broad transverse black stripes over the back and tail give the animal its common name of "tiger." The thylacine (q.v.) is a wolf-like derivative of the dasyuroid stock, specialized for long-distance running. Its skull is elongate, in contrast with the very broad short skull of Sarcophilus. The molar teeth, although adapted for shearing flesh, differ markedly from those of the dasyures and Sarcop/iilus. The upper molars have lost the accessory cusps on the outer side of the crown, the internal spurs of the upper molars are subcircular, the two main external cusps are more or less approximated. In the lower molars the hinder spur or talonid is reduced, while the front part consists of two large blade like cusps, the metaconid or hinder inner cusp being totally wanting. The nearest resemblances in dentition and skull are found not in any other Australian forms but among the extinct borhyaenids of the Patagonian Miocene. On the other hand, Thylacinus agrees closely with the Australian dasyuroids in many important details, so that there seems little doubt of its deriva tion from an Australian dasyuroid stock. The further significance of these facts will be discussed below. The thylacine formerly inhabited the mainland of Australia, its fossil remains having been found in caves; but during historic times it has lived only in Tasmania. As it was destructive to sheep it has been almost exterminated and survives only in the mountains.
Under the Australian dasyuroid series we include the banded anteater or wombat (Myrmecobius) of South and West Australia.
This very rare animal is now almost extinct. In general appear ance it strongly recalls other small dasyuroids, having a long pointed muzzle and long ears, somewhat like Antechinomys, a transversely striped back, recalling Thylacinus and certain bandi coots, a bushy tail, like that of the brush-tailed pouched mouse.
Moreover it is pouchless and the large foetuses are carried on the nipples, exposed as in Dasycercus. The high number of molars (sometimes rising to five in the upper and six in the lower jaws) may be regarded as a secondary increase in number correlated with reduction in size and spreading out of the teeth, in connec tion with an elongate, cylindrical extensible tongue, and a back wardly prolonged palate. A comparative study of the entire skeleton of Myrmecobius leads to the conclusion that it is thoroughly dasyuroid in type. A fossil lower jaw from the basal Eocene of Montana, named Myrmecoboides montanensis, helps us to visualize the process by which more normal insectivorous lower molars could readily be modified into the Myrmecobius type by suppression of the main outer cusps on the lower molars and of the inner cusps of the upper molars, this producing what I. W. Gidley has well named a "pseudotriconodont" type. The fossil jaw itself, however, is probably not at all related to Myrme cobius, since it agrees with the extinct placental insectivores of the family Lepticitidx in its dental formula and in the family characters of the teeth.
A most highly aberrant dasyuroid is the pouched mole (No toryctes) of South and Western Australia. The general appearance is like that of the African golden mole (Chrysochloris). In adaptation to its digging habits the conical head ends in front in a horny shield over the nose and evidently the head must be pushed into the soil. The neck vertebrae are fused to give it a firm support. The hands are provided with two enormous claws on the third and fourth fingers, the first and second fingers bearing much smaller claws which are opposable to the inner surfaces of the large outer claws. The fifth finger is very short and capped with a horny boss. The body is thick and cylindrical and the tail very short and covered with horny rings. The hind feet are short and spreading, with long digging claws. The eyes are degenerate, almost vestigial, and there are no external ears.