Evidence for Megalake Chad, north-central Africa, during the late Quaternary from satellite data

Leblanc, Marc; Leduc, Christian; Stagnitti, Frank; Oevelen, P.J. van; Jones, Christopher B.; Mofor, Linus; Razack, Moumtaz; Favreau, Guillaume

doi:10.1016/j.palaeo.2005.07.016

Cited by 55 publications

(31 citation statements)

References 12 publications

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“…These climatic variations have often been extreme, characterized by variations in rainfall and evaporation causing the expansion, contraction, or even complete disappearance of river systems (John, 1986; Leblanc et al . 2006a, b; Sepulchre et al ., 2008). Potential barriers to gene flow between C. emini and Cricetomys sp.…”

Section: Discussionmentioning

confidence: 99%

Taxonomy of the African giant pouched rats (Nesomyidae: Cricetomys): molecular and craniometric evidence support an unexpected high species diversity

Olayemi

Nicolas

Hulselmans

et al. 2012

Zoological Journal of the Linnean Society

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Our study combined a mitochondrial cytochrome b phylogeny with cranial measurements from giant pouched rats collected across sub‐Saharan Africa. The mitochondrial phylogeny resolves two West African clades and a clade with east and central Africa representatives. This last clade can be further divided into four subclades. Altogether they represent six species (Cricetomys gambianus, Cricetomys ansorgei, Cricetomys emini, and three undescribed taxa) that can be distinguished on the basis of their mitochondrial DNA sequences and craniometry. In the absence of adequate craniometric data the existence of Cricetomys kivuensis cannot be confirmed by our data. Our combined molecular and craniometric data allowed us to broadly delineate the distribution ranges of the detected species. Cricetomys gambianus occurs in the savannah and forest clearings of West Africa. Cricetomys ansorgei is distributed in the savannah of East and southern Africa. Cricetomys emini, as currently recognized across the Guineo‐Congolian forest of Africa, is shown to be diphyletic. Cricetomys sp. 1, a separate operational taxonomic unit closely resembling C. emini, occurs in the forest zone of West Africa. An undescribed sister‐species of C. ansorgei, Cricetomys sp. 2, occurs in the forest of Central Africa along the left bank of the Congo River. Cricetomys sp. 3 occurs on the right bank of the Congo River from Cameroon to the Republic of Congo, whereas the true C. emini also occurs on the right bank of the Congo River but appears to be restricted to the Democratic Republic of Congo. Cranial phenotype within the genus tends to conform to ecological zonation (either forest or savannah) rather than to phylogenetic affiliation of the species concerned, suggesting that diversifying selection across environmental gradients could be responsible for biological diversification within the genus.

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Section: Discussionmentioning

confidence: 99%

Taxonomy of the African giant pouched rats (Nesomyidae: Cricetomys): molecular and craniometric evidence support an unexpected high species diversity

Olayemi

Nicolas

Hulselmans

et al. 2012

Zoological Journal of the Linnean Society

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“…The latter was the largest freshwater lake in Africa and probably the largest pluvial lake on Earth. During the Early to mid-Holocene wet phase, Lake Mega-Chad attained an area of 361,000 km 2 (16)(17)(18) and a depth of up to 160 m (Fig. 1).…”

Section: West African Monsoon Dynamicsmentioning

confidence: 99%

West African monsoon dynamics inferred from abrupt fluctuations of Lake Mega-Chad

Armitage

Bristow

Drake

2015

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

130

116

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From the deglacial period to the mid-Holocene, North Africa was characterized by much wetter conditions than today. The broad timing of this period, termed the African Humid Period, is well known. However, the rapidity of the onset and termination of the African Humid Period are contested, with strong evidence for both abrupt and gradual change. We use optically stimulated luminescence dating of dunes, shorelines, and fluviolacustrine deposits to reconstruct the fluctuations of Lake Mega-Chad, which was the largest pluvial lake in Africa. Humid conditions first occur at ∼15 ka, and by 11.5 ka, Lake Mega-Chad had reached a highstand, which persisted until 5.0 ka. Lake levels fell rapidly at ∼5 ka, indicating abrupt aridification across the entire Lake Mega-Chad Basin. This record provides strong terrestrial evidence that the African Humid Period ended abruptly, supporting the hypothesis that the African monsoon responds to insolation forcing in a markedly nonlinear manner. In addition, Lake Mega-Chad exerts strong control on global biogeochemical cycles because the northern (Bodélé) basin is currently the world’s greatest single dust source and possibly an important source of limiting nutrients for both the Amazon Basin and equatorial Atlantic. However, we demonstrate that the final desiccation of the Bodélé Basin occurred around 1 ka. Consequently, the present-day mode and scale of dust production from the Bodélé Basin cannot have occurred before 1 ka, suggesting that its role in fertilizing marine and terrestrial ecosystems is either overstated or geologically recent.

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“…Remote sensing has proved to be of great assistance in environmental change studies in arid regions (Castan˜eda et al, 2005;Ghoneim and El-Baz, 2007;Guo et al, 2000;Hartmann et al, 2003;Leblanc et al, 2006;Schuster et al, 2005). Here, remote sensing is employed to understand the spatial distribution of shorelines around Jilantai using interpretation of astronaut photographs coupled with analyses of Landsat-7 ETM+ images.…”

Section: Article In Pressmentioning

confidence: 99%

The Jilantai Salt Lake shorelines in Northwestern arid China revealed by remote sensing images

Yang

Chen

Xia

et al. 2008

Journal of Arid Environments

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Evidence for Megalake Chad, north-central Africa, during the late Quaternary from satellite data

Cited by 55 publications

References 12 publications

Taxonomy of the African giant pouched rats (Nesomyidae: Cricetomys): molecular and craniometric evidence support an unexpected high species diversity

Taxonomy of the African giant pouched rats (Nesomyidae: Cricetomys): molecular and craniometric evidence support an unexpected high species diversity

West African monsoon dynamics inferred from abrupt fluctuations of Lake Mega-Chad

The Jilantai Salt Lake shorelines in Northwestern arid China revealed by remote sensing images

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