Northeast African vegetation change over 12 m.y.

Feakins, Sarah J.; Levin, Naomi E.; Liddy, Hannah M.; Sieracki, A.; Eglinton, T. I.; Bonnefille, Raymonde

doi:10.1130/g33845.1

Cited by 162 publications

(131 citation statements)

References 27 publications

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“…2). Given that large, orbital-scale variability is observed in marine and terrestrial archives when sedimentation rates are high and sequences are adequately sampled (7,8,44), we conclude that some other factor may be smoothing or obscuring this orbital signal in our records. All of our sites were rotary drilled and, in some cases, spot cored, and coringrelated disturbance was observed in places.…”

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confidence: 81%

“…Another carbon isotope archive for reconstructing eastern African paleovegetation that has emerged as a powerful tool in the past decade is terrestrial plant waxes from sediments (7,8,44). Plant wax biomarkers derive primarily from epicuticular leaf waxes that protect the leaf tissue from abrasion by dust; attack from insects, microbes, and fungi; and water loss from the leaf surface.…”

Section: And References Therein)mentioning

confidence: 99%

“…Our lineage, the hominins, first appeared in the late Miocene or early Pliocene after splitting from chimpanzees between 7 Ma and 5 Ma based on molecular divergence rates (1,2). In the past few decades, new discoveries have greatly expanded the number of hominins in the fossil record, and, in concert, new paleoenvironmental records (3)(4)(5)(6)(7)(8) and syntheses (9)(10)(11) have expanded our understanding of hominin paleoenvironments in eastern Africa. The set of tools available for studying paleovegetation has also expanded considerably, and a diverse series of approaches are being used in eastern Africa.…”

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confidence: 99%

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Neogene biomarker record of vegetation change in eastern Africa

Uno

Polissar

Jackson

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

126

103

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The evolution of C4 grassland ecosystems in eastern Africa has been intensely studied because of the potential influence of vegetation on mammalian evolution, including that of our own lineage, hominins. Although a handful of sparse vegetation records exists from middle and early Miocene terrestrial fossil sites, there is no comprehensive record of vegetation through the Neogene. Here we present a vegetation record spanning the Neogene and Quaternary Periods that documents the appearance and subsequent expansion of C4 grasslands in eastern Africa. Carbon isotope ratios from terrestrial plant wax biomarkers deposited in marine sediments indicate constant C3 vegetation from ∼24 Ma to 10 Ma, when C4 grasses first appeared. From this time forward, C4 vegetation increases monotonically to present, with a coherent signal between marine core sites located in the Somali Basin and the Red Sea. The response of mammalian herbivores to the appearance of C4 grasses at 10 Ma is immediate, as evidenced from existing records of mammalian diets from isotopic analyses of tooth enamel. The expansion of C4 vegetation in eastern Africa is broadly mirrored by increasing proportions of C4-based foods in hominin diets, beginning at 3.8 Ma in Australopithecus and, slightly later, Kenyanthropus. This continues into the late Pleistocene in Paranthropus, whereas Homo maintains a flexible diet. The biomarker vegetation record suggests the increase in open, C4 grassland ecosystems over the last 10 Ma may have operated as a selection pressure for traits and behaviors in Homo such as bipedalism, flexible diets, and complex social structure.

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confidence: 81%

Section: And References Therein)mentioning

confidence: 99%

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confidence: 99%

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Neogene biomarker record of vegetation change in eastern Africa

Uno

Polissar

Jackson

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

126

103

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“…Plant waxes are commonly preserved in sedimentary organic matter where their resistance to diagenetic alteration and isotope exchange makes them an excellent vegetation proxy [33][34][35]. Several studies have used plant wax isotopes from marine [36,37] and lacustrine [38,39] sediments ranging in age from recent to ca 12 Ma to reconstruct African vegetation; however, none to date have used plant waxes in palaeosols or fluvial sediments for vegetation reconstructions in eastern Africa. Alkyl lipids in Turkana Basin sediments were first evaluated over 30 years ago [40], before the advent of compound specific isotope analysis [41].…”

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confidence: 99%

A Pleistocene palaeovegetation record from plant wax biomarkers from the Nachukui Formation, West Turkana, Kenya

Uno

Polissar

Kahle

et al. 2016

Phil. Trans. R. Soc. B

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One contribution of 17 to a discussion meeting issue 'Major transitions in human evolution'. Reconstructing vegetation at hominin fossil sites provides us critical information about hominin palaeoenvironments and the potential role of climate in their evolution. Here we reconstruct vegetation from carbon isotopes of plant wax biomarkers in sediments of the Nachukui Formation in the Turkana Basin. Plant wax biomarkers were extracted from samples from a wide range of lithologies that include fluvial-lacustrine sediments and palaeosols, and therefore provide a record of vegetation from diverse depositional environments. Carbon isotope ratios from biomarkers indicate a highly dynamic vegetation structure (ca 5-100% C 4 vegetation) from 2.3 to 1.7 Ma, with an overall shift towards more C 4 vegetation on the landscape after about 2.1 Ma. The biomarker isotope data indicate ca 25-30% more C 4 vegetation on the landscape than carbon isotope data of pedogenic carbonates from the same sequence. Our data show that the environments of early Paranthropus and Homo in this part of the Turkana Basin were primarily mixed C 3 -C 4 to C 4 -dominated ecosystems. The proportion of C 4 -based foods in the diet of Paranthropus increases through time, broadly paralleling the increase in C 4 vegetation on the landscape, whereas the diet of Homo remains unchanged. Biomarker isotope data associated with the Kokiselei archaeological site complex, which includes the site where the oldest Acheulean stone tools to date were recovered, indicate 61-97% C 4 vegetation on the landscape.This article is part of the themed issue 'Major transitions in human evolution'.

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“…(Garcin et al, 2014) and insensitivity to changes within C 3 photosynthetic ecosystems (i.e. woody vs. non-woody Feakins et al, 2013;Magill et al, 2013a,b). Additionally, spatial integration is likely not uniform within a river catchment, as changes in plant-wax distribution and isotope signals have been observed during fluvial transit Ponton et al, 2014).…”

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confidence: 99%

Understanding terrestrial organic carbon export : a time-series approach

Hemingway¹

2017

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Northeast African vegetation change over 12 m.y.

Cited by 162 publications

References 27 publications

Neogene biomarker record of vegetation change in eastern Africa

Neogene biomarker record of vegetation change in eastern Africa

A Pleistocene palaeovegetation record from plant wax biomarkers from the Nachukui Formation, West Turkana, Kenya

Understanding terrestrial organic carbon export : a time-series approach

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