Stable isotope analysis of carnivores from the Turkana Basin, Kenya: Evidence for temporally-mixed fossil assemblages
Stable isotope analysis of carnivores from the Turkana Basin, Kenya: Evidence for temporally-mixed fossil assemblages
复制标题
肯尼亚图尔卡纳盆地食肉动物的稳定同位素分析：时间混合化石组合的证据
DOI：
10.1016/j.quaint.2022.04.004
复制
发表时间：
2023
影响因子：
2.2
通讯作者：
Leakey, Louise N.
中科院分区：
文献类型：
--
作者：
Hopley, Philip J.;Cerling, Thure E.;Crété, Lucile;Werdelin, Lars;Mwebi, Ogeto;Manthi, Fredrick K.;Leakey, Louise N.
哺乳动物化石的稳定同位素古生态学是理解非洲更新世-更新世人类进化环境的关键研究工具。研究得很好的哺乳动物包括牛、猪、马、鼻目动物和灵长类动物，但到目前为止，还没有对现代和化石食肉动物进行深入研究。在这里，我们为现代食肉动物制作了一个全非洲范围的氧和碳珐琅同位素数据集，并将其与肯尼亚图尔卡纳盆地上更新世Omo群中的食肉动物化石数据进行了比较。现代食肉动物碳同位素与卫星陆地覆盖图像的对比表明，食肉动物δ13C与当地环境中木本植物覆盖的比例有关。现代食肉动物的氧同位素受到大气水的δ18O的强烈影响，通过饮用死水和通过猎物体液。来自食肉动物化石的碳同位素数据与同一地质段古土壤碳酸盐的δ~(13)C古植被重建结果非常吻合，δ~(13)C值随时间(4 Ma~1 Ma)的变化趋势相似，反映了图尔卡纳盆地C4草所占比例的逐渐增加。大型食肉动物δ13C的这种增加与来自其他哺乳动物群体的证据一致，即在这一时间间隔内，与食草动物和混合食肉动物相比，食草动物的比例有所增加。氧和碳同位素空间的两个不同趋势表明，食肉化石生活在两个不同的气候体制中--一个是图尔卡纳湖是淡水古湖，另一个是图尔卡纳湖类似于现代的高碱性状态。这两个气候状态很可能代表了埃塞俄比亚高地上由前驱使的极端降雨的结束成员。这表明，来自Omo群的每个所研究的动物群组合都是一个时间和气候平均的回文；这对解释环境信号和源自图尔卡纳盆地哺乳动物化石(包括早期人类)的群落古生态具有重要意义。
Stable isotope palaeoecology of fossil mammals is a key research tool for understanding the environmental context of hominin evolution in the Plio-Pleistocene of Africa. Well studied mammal groups include bovids, suids, equids, proboscideans and primates, but to date there has been no in-depth study of modern and fossil carnivores. Here we produce an Africa-wide oxygen and carbon enamel isotope dataset for modern carnivores and compare it with fossil carnivore data sampled from the Plio-Pleistocene Omo Group of the Turkana Basin, Kenya. Comparison of modern carnivore carbon isotopes with satellite images of land cover indicates that carnivore δ13C is related to the proportion of woody cover in the local environment. Modern carnivore oxygen isotopes are strongly influenced by the δ18O of meteoric water, through drinking from standing water and through prey body fluids. Carbon isotope data from fossil carnivores shows close agreement with palaeovegetation reconstructions from δ13C of palaeosol carbonates from the same geological Members, and a similar long-term trend in δ13C values through time (4 Ma to 1 Ma), reflecting a gradual increase in the proportion of C4grasses in the Turkana Basin. This increase in the δ13C of large carnivores is consistent with the evidence from other mammalian groups for an increase in the proportion of grazers compared to browsers and mixed feeders during this time interval. Two distinct trends within oxygen versus carbon isotope space indicates that the fossil carnivores lived during two distinct climatic regimes – one in which palaeo-lake Turkana was freshwater, and one in which the lake resembled its modern-day hyperalkaline state. These two climatic states most likely represent the end-members of precessionally-driven rainfall extremes over the Ethiopian Highlands. This indicates that each studied faunal assemblage from the Omo Group is a time- and climate-averaged palimpsest; this has significant implications for the interpretation of environmental signals and community palaeoecology derived from Turkana Basin fossil mammals, including early hominins.