All Australian land mammals, reptiles, and birds weighing more than 100 kilograms, and six of the seven genera with a body mass of 45 to 100 kilograms, perished in the late Quaternary. The timing and causes of these extinctions remain uncertain. We report burial ages for megafauna from 28 sites and infer extinction across the continent around 46,400 years ago (95% confidence interval, 51,200 to 39,800 years ago). Our results rule out extreme aridity at the Last Glacial Maximum as the cause of extinction, but not other climatic impacts; a "blitzkrieg" model of human-induced extinction; or an extended period of anthropogenic ecosystem disruption.

Aim  To assess whether eight factors thought to be involved in the extinction process can explain the pattern of recent decline in Australia's mammal fauna. Location  Australia. Methods  We compiled the first comprehensive lists of mammal species extant at the time of European settlement in each of Australia's 76 mainland regions, and assigned a current conservation status to each species in each region to derive an index of faunal attrition. We then sought to explain the observed region‐to‐region variation in attrition (the dependent variable) by building a series of models using variables representing the eight factors. Results  A strong geographically based pattern of attrition emerged, with faunal losses being greatest in arid regions and least in areas of high rainfall. The Akaike information criterion showed support for one model that explained 93% of the region‐to‐region variation in attrition. Its six variables all made independent contributions towards explaining the observed variation. Two were environmental variables, namely mean annual rainfall (a surrogate for regional productivity) and environmental change (a measure of post‐European disturbance). The other four were faunal variables, namely phylogenetic similarity, body‐weight distribution, area (as a surrogate for extent of occurrence), and proportion of species that usually shelter on the ground (rather than in rock piles, burrows or trees). Main conclusions  In combination with historical evidence, the analysis provides an explicit basis for setting priorities among regions and species. It also shows that the long‐term recovery of populations of many species of Australian mammals will require introduced predator suppression as well as extensive habitat management that includes controlling feral herbivores. Specifically, habitat management should restore aspects of productivity relevant to the types of species at risk and ensure the continual availability of suitable refuges from physiological stressors.

This paper attempts to identify and explain patterns in the biogeography of Australia’s indigenous terrestrial mammals at the time of European settlement (before modern extinctions), and also compares species’ pre-European and current status by region. From subfossil, historical and contemporary sources, we compiled data on the past geographic range and present status of mammals for Australia’s 85 biogeographic regions. Of the 305 indigenous species originally present, 91 have disappeared from at least half of the bioregions in which they occurred before European settlement. Thirty-nine extant species ‘persist’ in less than 25% of their original bioregions; 28 of these are marsupials and 11 are rodents. Twenty-two of the original 305 species are extinct, a further eight became restricted to continental islands, and 100 have become extinct in at least one bioregion. Over the same period, 26 species of exotic mammals established wild populations and now occupy from one to 85 bioregions. When we classified the bioregions in terms of their original species composition, the 3-group level in the dendrogram approximated the Torresian, Eyrean and Bassian subregions proposed by Spencer in 1898, while the 4-group level separated southern semiarid Eyrean bioregions, including those in south-west Australia, from the arid Eyrean bioregions. The classification dendrogram showed geographically (and statistically) discrete clustering down to the 19-group level, suggesting that all four subregions can be further divided on the basis of their mammal faunas. Variation partitioning showed 66% of the biogeographical pattern can be explained by environmental factors (related to temperature and precipitation), the spatial position of each bioregion (a third-order polynomial of latitude and longitude), the area of each bioregion, and the richness of species in each bioregion. In addition to the marked distributional changes that indigenous mammals have experienced over the last 200 years, the 49% of variation explainable by temperature and precipitation implies further shifts with global climate change.