A Photographic Guide to Mammals of Australia [antikvár]

Introduction Australia is famous for its kangaroos. Koala and other marsupials. It is also home to the Platypus and Short-beaked Echidna, which are egg-laying mammals. Otherwise its representation of the diversity of the world's terrestrial mammals is remarkably low. Of the 17 major groups (orders) of mammals, only two others - the bats and the rodents - occur in its basically native fauna. There is a popular belief that marsupials are restricted to Australia but close relatives of the Australian species are found from the eastern end of the Indonesian Archipelago (east of Bali), through New Guinea to the Solomon Islands. Much more distantly related species occur from Patagonia to the Isthmus of Panama and one marsupial is common in North America. The Platypus is restricted to the eastern seaboard of Australia but the related Short-beaked Echidna extends into the lowlands of New Guinea and the rare and little-known Long-beaked Echidna lives in the mist forests of the New Guinea Highlands. This strange distribution is not easily understood in terms of the present geography of this planet but a plausible explanation can be offered in terms of the movements of continents over very long periods. About 160 million years ago, the land surface of the world was concentrated into two masses, a northern Laurasia and a southern Gondwanaland, comprising the elements that later separated into Africa, Madagascar, India, Australia, Antarctica, New Zealand and South America. These gradually separated - India moving into the northern hemisphere to collide with Asia - but South America, Antarctica and Australia remained connected until about 45 million years ago. Before that time, South America had a diverse fauna of marsupials and at least one platypus-like monotreme, so it seems likely that representatives of these groups moved from Patagonia, across a much warmer Antarctica, into Australia. When the Australian landmass (including what is now New Guinea) finally separated from Antarctica, the only mammals on the continent were marsupials and monotremes. From that time, until about 20 million years ago, they had the continent to themselves and, given a wealth of opportunities, these pioneers provided the basis of an enormous evolutionary radiation. The end results of the monotreme radiation are the semi-aquatic Platypus, feeding on invertebrates at the bottom of rivers and lakes; and the decidedly terrestrial, spiny-furred echidnas, one specialised for a diet of ants, the other feeding mainly on worms in tropical leaf-litter. There may well have been other monotremes but fossil remains are so sparse that this question must be left open. The diversity of living marsupials provides evidence of an extensive radiation. They include large and small carnivores, insectivores (including the Numbat which feeds on termites), browsers, grazers and nectar-feeders. There are fast runners, hopping species, burrowers, climbers and gliders. Habitats exploited range from tropical rainforest to stony deserts and alpine regions but, interestingly, there is no Australian aquatic marsupial equivalent to the Yapock of South America. In size, marsupials range from some that are small enough to fit into a matchbox, others weigh more than 60kg. As recently as 50 000 years ago, there were herbivorous species the size of hippopotamus. Some 15 million to 20 million years ago, the Australian land-mass had moved so far northward that its continental shelf collided