However, he found none of these in Lombok. In general, the areas west of the Wallace line are dominated by placental mammals, east of the line are almost entirely marsupials and birds. The striking contrast between the two biogeographic areas are described in detail by Wallace in one of his journal entries. The Australian and Indian regions of Zoology are very strongly contrasted. Of all the varied forms of Quadrumana, Carnivora, Insectivora, and Ruminantia which abound in the western half of the Archipelago, the only genera found in the Moluccas are Paradoxurus and Cervus.
Birds furnish equally remarkable illustrations.
Three entire families of the Psittacine order are peculiar to the former region, and two of them, the Cockatoos and the Lories, extend up to its extreme limits, without a solitary species passing into the Indian islands of the Archipelago. The genus Tropidorhynchus, highly characteristic of the Australian region, and everywhere abundant as well in the Moluccas and New Guinea as in Australia, is quite unknown in Java and Borneo. Australia was one part of Gondwana a massive peninsula of the supercontinent Pangaea. It consisted of most of the southern continents and was separated from the northern continents by the Tethys sea for over 500 millions years. Over that time, pieces have broken off and everything has drifted to the north, closing the gap to Eurasia.