The lunettes at Mungo and other dry lakes along Willandra Creek in western New South Wales have provided the best dated late Pleistocene geomorphological sequence for Australia. They also contain the oldest archaeological material, including human burials and cremations, in Australia, but the remains of extinct Pleistocene mammal species are extremely rare. At Menindee and other lakes along the Darling River, 150 km to the west, lunettes of apparently similar age contain both archaeological material and abundant fossils of extinct species. The rarity of such fossils along the Willandra Lakes has been cited as evidence that the extinction of the Pleistocene species occurred before 30,000 BP. However, a comparison of the Darling and Willandra sites in terms of taphonomy and palaeoecology leads to the conclusion that these sites do not yet provide any definitive evidence for the time or causes of the Pleistocene extinctions.