Lüdecke Tina, Schrenk Friedemann, Thiemeyer Heinrich, Kullmer Ottmar, Bromage Timothy G, Sandrock Oliver, Fiebig Jens, Mulch Andreas
Senckenberg Biodiversity and Climate Research Centre, Senckenberganlage 25, 60325 Frankfurt, Germany; Institute of Geosciences, Goethe University Frankfurt, Altenhöferallee 1, 60438 Frankfurt, Germany.
Senckenberg Biodiversity and Climate Research Centre, Senckenberganlage 25, 60325 Frankfurt, Germany; Institute for Ecology, Evolution, and Diversity, Johann Wolfgang Goethe University, Max-von-Laue-Str. 13, 60438 Frankfurt, Germany.
J Hum Evol. 2016 Jan;90:163-75. doi: 10.1016/j.jhevol.2015.10.014. Epub 2015 Dec 1.
The development of East African savannas is crucial for the origin and evolution of early hominins. These ecosystems, however, vary widely in their fraction of woody cover and today range from closed woodland to open grassland savanna. Here, we present the first Plio-Pleistocene long-term carbon isotope (δ(13)C) record from pedogenic carbonate and Suidae teeth in the southern East African Rift (EAR). These δ(13)C data from the Chiwondo and Chitimwe Beds (Karonga Basin, Northern Malawi) represent a southern hemisphere record in the EAR, a key region for reconstructing vegetation patterns in today's Zambezian Savanna, and permit correlation with data on the evolution and migration of early hominins in today's Somali-Masai Endemic Zone. The sediments along the northwestern shore of Lake Malawi contain fossils attributed to Homo rudolfensis and Paranthropus boisei. The associated hominin localities (Uraha, Malema) are situated between the well-known hominin bearing sites of the Somali-Masai Endemic Zone in the Eastern Rift and the Highveld Grassland in southern Africa, and fill an important geographical gap for hominin research. Persistent δ(13)C values around -9‰ from pedogenic carbonate and suid enamel covering the last ∼4.3 Ma indicate a C3-dominated closed environment with regional patches of C4-grasslands in the Karonga Basin. The overall fraction of woody cover of 60-70% reflects significantly higher canopy density in the Malawi Rift than the Eastern Rift through time. The discrepancy between the two savanna types originated in the Late Pliocene, when the Somali-Masai ecosystem started to show increasing evidence for open, C4-dominated landscapes. Based on the Malawi δ(13)C data, the evolution of savanna ecosystems in Eastern Africa followed different patterns along the north-south extent of the EAR. The appearance of C4-grasses is considered a driver of evolutionary faunal shifts, but despite the difference of ecosystem evolution in the north, similar hominins and suids occurred in both landscapes, pointing to distinct habitat flexibility and also nutritional versatility.
东非稀树草原的发展对早期人类的起源和进化至关重要。然而，这些生态系统的木本覆盖比例差异很大，如今涵盖了从封闭林地到开阔草原稀树草原的范围。在此，我们展示了东非大裂谷（EAR）南部来自成土碳酸盐和猪科动物牙齿的首个上新世 - 更新世长期碳同位素（δ(13)C）记录。这些来自奇翁多和奇蒂姆韦层（马拉维北部卡龙加盆地）的δ(13)C数据代表了东非大裂谷的南半球记录，这是重建当今赞比西稀树草原植被模式的关键区域，并允许与当今索马里 - 马赛特有区域早期人类的进化和迁徙数据进行对比。马拉维湖西北岸的沉积物中含有归因于鲁道夫智人和鲍氏傍人的化石。相关的人类遗址（乌拉哈、马勒马）位于东裂谷中著名的索马里 - 马赛特有区域人类遗址与南部非洲高地草原之间，填补了人类研究中的一个重要地理空白。覆盖过去约430万年的成土碳酸盐和猪科动物牙釉质的δ(13)C值持续在约 -9‰左右，表明卡龙加盆地是一个以C3为主的封闭环境，局部有C4草原。随着时间推移，木本覆盖的总体比例为60 - 70%，这反映出马拉维裂谷的冠层密度明显高于东裂谷。这两种稀树草原类型之间的差异始于上新世晚期，当时索马里 - 马赛生态系统开始有越来越多证据表明出现了开阔的、以C4为主的景观。基于马拉维的δ(13)C数据，东非稀树草原生态系统的演化在东非大裂谷的南北范围内遵循不同模式。C4草的出现被认为是动物群进化转变的一个驱动因素，但尽管北部生态系统演化存在差异，两个区域都出现了相似的人类和猪科动物，这表明它们具有独特的栖息地适应性和营养多样性。
