Australia. The most interesting fact in connexion with the Tertiary Polyprotodonts is the existence in South America of such genera as Prothylacinus and Amphiproviverra, which are not merely Polyprotodonts but definitely Dasyures, and not referable to the Didelphyidae.
These forms have been included in an order, Sparassodonta. But it is not by any means certain whether these forms are rightly placed in the neighbourhood of the carnivorous Marsupials; it is possible that they ought to be relegated to the Creodonta or to their allies. Their structure is in fact somewhat intermediate between those two groups. The teeth seem to be carnivorous and Marsupial-like in form; but as already mentioned, in connexion with the general structure of teeth, more than a single premolar is replaced. These animals in fact, in so far as regards their teeth, are midway between the Marsupials and the typical Eutheria. The angle of the lower jaw is inflected, but the palate is not marked by deficient ossification. At least this is not the case with all the members of the group. Whether the small Microbiotherium, which is made the type of a family, is rightly referred here is not certain. This animal had palatine vacuities as well as an inflected angle to the lower jaw.
