Constrained seriation of a species-locality matrix of the Australian Cenozoic mammal record resolves a preliminary sixfold succession of land mammal ages apparently spanning the late Oligocene to the present. The applied conditions of local chronostratigraphic succession and inferences of relative stage-of-evolution biochronology lead to the expression of a continental geological timescale consisting of, from the base, the Etadunnan, Wipajirian, Camfieldian, Waitean, Tirarian, and Naracoortean land mammal ages. Approximately 99% of the 360 fossil assemblages analyzed are classifiable using this method. Each is characterized by a diagnostic suite of species. An interval of age magnitude may eventually be shown to lie between the Camfieldian and Waitean, but is currently insufficiently represented by fossils to diagnose. Development of a land mammal age framework marks a progressive step in Australian vertebrate biochronology, previously expressed only in terms of local faunas. Overall, however, the record remains poorly calibrated to the Standard Chronostratigraphic Scale. Codifying the empirical record as a land mammal age sequence provides an objective basis for expressing faunal succession without resort to standard chronostratigraphic terms with the attendant (and hitherto commonly taken) risks of miscorrelating poorly dated Australian events to well-dated global events.

Kangaroos are the world's most diverse group of herbivorous marsupials. Following late-Miocene intensification of aridity and seasonality, they radiated across Australia, becoming the continent's ecological equivalents of the artiodactyl ungulates elsewhere. Their diversity peaked during the Pleistocene, but by approximately 45,000 years ago, 90% of larger kangaroos were extinct, along with a range of other giant species. Resolving whether climate change or human arrival was the principal extinction cause remains highly contentious. Here we combine craniodental morphology, stable-isotopic, and dental microwear data to reveal that the largest-ever kangaroo, Procoptodon goliah, was a chenopod browse specialist, which may have had a preference for Atriplex (saltbushes), one of a few dicots using the C 4 photosynthetic pathway. Furthermore, oxygen isotope signatures of P. goliah tooth enamel show that it drank more in low-rainfall areas than its grazing contemporaries, similar to modern saltbush feeders. Saltbushes and chenopod shrublands in general are poorly flammable, so landscape burning by humans is unlikely to have caused a reduction in fodder driving the species to extinction. Aridity is discounted as a primary cause because P. goliah evolved in response to increased aridity and disappeared during an interval wetter than many it survived earlier. Hunting by humans, who were also bound to water, may have been a more decisive factor in the extinction of this giant marsupial.Australia ͉ dietary ecology ͉ extinct marsupial ͉ stable isotopes ͉ human hunting

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The Late Oligocene Kangaroo Well Local Fauna from the Ulta Limestone (new name), northwestern Lake Eyre Basin correlates best with vertebrate assemblages from the Etadunna, Namba and Wipajiri Formations of the central Lake Eyre Basin, and from the Carl Creek Limestone (Karumba Basin) of northwestern Queensland. The biochronologically informative marsupials, Neohelos tirarensis (Diprotodontidae, Zygomaturinae), Marlu sp. cf. M. kutjamarpensis and Pildra sp. cf. P. magnus (Pseudocheiridae), and Ektopodon ulta sp. nov. (Ektopodontidae), indicate that the Kangaroo Well Local Fauna may be slightly older than the Kutjamarpu Local Fauna (Wipajiri Formation) and slightly younger than the Ngama Local Fauna (zone D of the Etadunna Formation) of Late Oligocene age. A new species of primitive ?Wynyardiidae, Ayekaye jaredi sp. nov., is described, and the nomenclature of two extinct gastropods, Glyptophysa rodingae (McMichael) and Cupedora lloydi (McMichael) (new combinations), the type localities of which are in the Ulta Limestone, is revised in line with current taxonomy. The Ulta Limestone, an alluvial calclithite composed primarily of caliche fabrics, and its correlatives were deposited during the Miocene oscillation climatic event. Palaeoclimatic modelling using sedimentological data, crocodilians and extant analogs of fossil terrestrial gastropods indicates that the average annual temperature at Kangaroo Well during the Late Oligocene was probably between 14 and 20°C, while mean annual rainfall was probably <600 mm. Similar associations from central parts of the Lake Eyre Basin, from Riversleigh, northwestern Queensland, and from Bullock Creek, north‐central Northern Territory, indicate that such conditions were widespread during depositional phases of the Miocene oscillation. Palaeoclimatic indicators do not support the presence of widespread closed forests in northwestern Queensland and across the inland of the Northern Territory and South Australia during the Miocene oscillation.