Data from: Dietary responses of Sahul (Pleistocene Australia–New Guinea) megafauna to climate and environmental change

Throughout the late Quaternary, the Sahul (Pleistocene Australia–New Guinea) vertebrate fauna was dominated by a diversity of large mammals, birds, and reptiles, commonly referred to as megafauna. Since ca. 450–400Ka, approximately 88 species disappeared in Sahul, including kangaroos exceeding 200kg in size, wombat-like animals the size of hippopotamuses, flightless birds, and giant monitor lizards that were likely venomous. Ongoing debates over the primary cause of these extinctions have typically favored climate change or human activities. Improving our understanding of the population biology of extinct megafauna as more refined paleoenvironmental data sets become available will assist in identifying their potential vulnerabilities. Here, we apply a multiproxy approach to analyze fossil teeth from deposits dated to the middle and late Pleistocene at Cuddie Springs in southeastern Australia, assessing relative aridity via oxygen isotopes as well as vegetation and megafaunal diets using both carbon isotopes and dental microwear texture analyses. We report that the Cuddie Springs middle Pleistocene fauna was largely dominated by browsers, including consumers of C4 shrubs, but that by late Pleistocene times the C4 dietary component was markedly reduced. Our results suggest dietary restriction in more arid conditions. These dietary shifts are consistent with other independently derived isotopic data from eggshells and wombat teeth that also suggest a reduction in C4 vegetation after ~45 Ka in southeastern Australia, coincident with increasing aridification through the middle to late Pleistocene. Understanding the ecology of extinct species is important in clarifying the primary drivers of faunal extinction in Sahul. The results presented here highlight the potential impacts of aridification on marsupial megafauna. The trend to increasingly arid conditions through the middle to late Pleistocene (as identified in other paleoenvironmental records and now also observed, in part, in the Cuddie Springs sequence) may have stressed the most vulnerable animals, perhaps accelerating the decline of late Pleistocene megafauna in Australia.

沙虎大陆（Sahul，即更新世澳大利亚-新几内亚区域）在晚第四纪时期的脊椎动物群以多样的大型哺乳类、鸟类和爬行类为主体，这类生物通常被称为巨型动物群（megafauna）。约距今45万至40万年以来，沙虎大陆共有约88个物种灭绝，其中包括体重超200千克的袋鼠、体型堪比河马的袋熊类动物、不会飞行的鸟类，以及大概率带有毒性的巨型巨蜥。目前针对此次灭绝事件的核心成因仍存在持续争论，主流观点主要聚焦于气候变化或人类活动两大方向。随着愈发精准的古环境数据集问世，加深对已灭绝巨型动物群种群生物学的认知，将有助于揭示它们潜在的生存脆弱性。本研究采用多代理分析方法，对澳大利亚东南部卡德斯普林斯（Cuddie Springs）遗址中更新世中晚期地层出土的化石牙齿展开研究：通过氧同位素分析评估相对干旱程度，同时利用碳同位素分析与牙齿微磨耗纹理分析，重建古植被与巨型动物群的食性。研究结果显示，卡德斯普林斯遗址更新世中期的动物群以植食性物种为主，其中包含依赖C4灌木的类群，但至更新世晚期，依赖C4植被的食性占比显著下降。本研究结果表明，在更为干旱的环境中，巨型动物群的食性范围受到限制。这类食性转变与此前从蛋壳与袋熊牙齿中独立获取的同位素数据结果一致：后者同样显示，澳大利亚东南部在距今约4.5万年以来C4植被覆盖率有所下降，这与更新世中晚期持续加剧的干旱化过程相吻合。厘清已灭绝物种的生态特征，有助于阐明沙虎大陆脊椎动物群灭绝的核心驱动因素。本研究结果凸显了干旱化过程对有袋类巨型动物群的潜在影响。更新世中晚期持续加剧的干旱化趋势（已被其他古环境记录证实，本次研究的卡德斯普林斯地层序列也部分印证了这一点），可能对生存能力最弱的物种造成生存压力，进而加速了澳大利亚更新世晚期巨型动物群的衰退。