The extinction of large-bodied terrestrial ‘megafauna’ during earlier phases of the Quaternary had a significant impact on the transforming structure of ecosystems. However, the causes of such losses remains difficult to determine in part because of a paucity of reliable geochronological information about the taxa involved. This is especially true for continents such as Australia where the majority of extinct species have never been dated using radiometric and/or luminescence methods. Here we add new understanding about the geochronology of the world's largest-ever marsupial, the giant wombat-like Diprotodon optatum, an iconic member of the large herbivore guild of Pleistocene Australia. We present 28 new direct U-series ages (dentine) and 10 luminescence ages (sediments) for D. optatum fossils from three sites in tropical north and subtropical eastern Australia. The luminescence ages lie close to saturation for the tropical northern site of Floraville and therefore indicate minimum ages, and sediments from Gowrie Creek in the Darling Downs were mixed and can only be stated as a likely age range. Nevertheless the results assist in our broader understanding of the timing of persistence of the species. Our results demonstrate that the species roamed the northern tropics at least until the mid-Pleistocene (ca. 420 ka). They likely remained widespread during Marine Isotope Stage 5 (ca. 110 ka) and were abundant on the Darling Downs of eastern Australia. The youngest of the new ages that we report (ca. 60 ka) are from Neds Gully on the Darling Downs, a catchment previously considered by some to contain among the last survivors of the now-extinct megafauna. The new dated record demonstrates that deposits of varying ages occur within the catchment. Consequently, existing species lists that treat Neds Gully as a single faunal assemblage are likely significantly time-averaged and overinflated in terms of palaeo-diversity.

第四纪早期大型陆生“巨型动物”的灭绝对生态系统的结构转型产生了重大影响。然而，这种损失的原因仍然难以确定，部分原因是缺乏有关所涉分类群的可靠地质年代信息。对于像澳大利亚这样的大陆来说尤其如此，那里的大多数灭绝物种从未使用辐射测量和/或发光方法确定日期。在这里，我们增加了对世界上有史以来最大的有袋动物——巨型袋熊Diprotodon optatum的地质年代学的新理解，它是澳大利亚更新世大型食草动物协会的标志性成员。我们为D. optatum提供了 28 个新的直接 U 系列年龄（牙本质）和 10 个发光年龄（沉积物）来自澳大利亚北部热带和亚热带东部三个地点的化石。热带北部 Floraville 站点的发光年龄接近饱和，因此表明最低年龄，来自 Darling Downs 的 Gowrie Creek 的沉积物是混合的，只能表示可能的年龄范围。然而，这些结果有助于我们更广泛地了解物种持续存在的时间。我们的结果表明，该物种至少在中更新世（约 420 ka）之前一直在北部热带地区漫游。它们可能在海洋同位素第 5 阶段（约 110 ka）期间仍然广泛存在，并且在澳大利亚东部的达令丘陵地区非常丰富。我们报告的新时代中最年轻的（约 60 ka）来自达令丘陵的 Neds Gully，以前有人认为这个集水区是现已灭绝的巨型动物的最后幸存者。新的日期记录表明流域内出现了不同年龄的沉积物。因此，将 Neds Gully 视为单一动物群组合的现有物种清单可能在古生物多样性方面具有显着的时间平均和过度膨胀。