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An ecometric analysis of the fossil mammal record of the Turkana Basin

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ABSTRACT

Although ecometric methods have been used to analyse fossil mammal faunas and environments of Eurasia and North America, such methods have not yet been applied to the rich fossil mammal record of eastern Africa. Here we report results from analysis of a combined dataset spanning east and west Turkana from Kenya between 7 and 1 million years ago (Ma). We provide temporally and spatially resolved estimates of temperature and precipitation and discuss their relationship to patterns of faunal change, and propose a new hypothesis to explain the lack of a temperature trend. We suggest that the regionally arid Turkana Basin may between 4 and 2 Ma have acted as a ‘species factory’, generating ecological adaptations in advance of the global trend. We show a persistent difference between the eastern and western sides of the Turkana Basin and suggest that the wetlands of the shallow eastern side could have provided additional humidity to the terrestrial ecosystems. Pending further research, a transient episode of faunal change centred at the time of the KBS Member (1.87–1.53 Ma), may be equally plausibly attributed to climate change or to a top-down ecological cascade initiated by the entry of technologically sophisticated humans.

This article is part of the themed issue ‘Major transitions in human evolution’.

No MeSH data available.


Comparison of turnover patterns in carnivorans and non-carnivorans in the Turkana basin. (a) Per capita origination showing earlier origination peak in carnivorans (2.2–1.9 Ma) than in non-carnivorans (1.9–1.6 Ma). Carnivoran origination peak at 3.4–3.1 is an artefact. (b): per capita extinctions showing carnivoran extinction peak at 2.8–2.5 Ma unmatched in non-carnivorans. Taking sampling into consideration suggests that this peak should be at 2.5–2.2 Ma (see Discussion for details). Solid line: carnivorans; dashed line: non-carnivorans.
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RSTB20150232F9: Comparison of turnover patterns in carnivorans and non-carnivorans in the Turkana basin. (a) Per capita origination showing earlier origination peak in carnivorans (2.2–1.9 Ma) than in non-carnivorans (1.9–1.6 Ma). Carnivoran origination peak at 3.4–3.1 is an artefact. (b): per capita extinctions showing carnivoran extinction peak at 2.8–2.5 Ma unmatched in non-carnivorans. Taking sampling into consideration suggests that this peak should be at 2.5–2.2 Ma (see Discussion for details). Solid line: carnivorans; dashed line: non-carnivorans.

Mentions: The results of the turnover analysis are shown in figure 9. Origination patterns are broadly similar in both sets of taxa, with the important exception that the early Pleistocene origination peak occurs one bin earlier in carnivorans than in non-carnivorans. Both datasets concur that origination is at a minimum in the late Pliocene (i.e. 2.8–2.5 Ma). The early Pliocene origination peaks are an edge effect and the difference in timing between carnivorans and non-carnivorans there owing to sampling.Figure 9.


An ecometric analysis of the fossil mammal record of the Turkana Basin
Comparison of turnover patterns in carnivorans and non-carnivorans in the Turkana basin. (a) Per capita origination showing earlier origination peak in carnivorans (2.2–1.9 Ma) than in non-carnivorans (1.9–1.6 Ma). Carnivoran origination peak at 3.4–3.1 is an artefact. (b): per capita extinctions showing carnivoran extinction peak at 2.8–2.5 Ma unmatched in non-carnivorans. Taking sampling into consideration suggests that this peak should be at 2.5–2.2 Ma (see Discussion for details). Solid line: carnivorans; dashed line: non-carnivorans.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4920289&req=5

RSTB20150232F9: Comparison of turnover patterns in carnivorans and non-carnivorans in the Turkana basin. (a) Per capita origination showing earlier origination peak in carnivorans (2.2–1.9 Ma) than in non-carnivorans (1.9–1.6 Ma). Carnivoran origination peak at 3.4–3.1 is an artefact. (b): per capita extinctions showing carnivoran extinction peak at 2.8–2.5 Ma unmatched in non-carnivorans. Taking sampling into consideration suggests that this peak should be at 2.5–2.2 Ma (see Discussion for details). Solid line: carnivorans; dashed line: non-carnivorans.
Mentions: The results of the turnover analysis are shown in figure 9. Origination patterns are broadly similar in both sets of taxa, with the important exception that the early Pleistocene origination peak occurs one bin earlier in carnivorans than in non-carnivorans. Both datasets concur that origination is at a minimum in the late Pliocene (i.e. 2.8–2.5 Ma). The early Pliocene origination peaks are an edge effect and the difference in timing between carnivorans and non-carnivorans there owing to sampling.Figure 9.

View Article: PubMed Central - PubMed

ABSTRACT

Although ecometric methods have been used to analyse fossil mammal faunas and environments of Eurasia and North America, such methods have not yet been applied to the rich fossil mammal record of eastern Africa. Here we report results from analysis of a combined dataset spanning east and west Turkana from Kenya between 7 and 1 million years ago (Ma). We provide temporally and spatially resolved estimates of temperature and precipitation and discuss their relationship to patterns of faunal change, and propose a new hypothesis to explain the lack of a temperature trend. We suggest that the regionally arid Turkana Basin may between 4 and 2 Ma have acted as a ‘species factory’, generating ecological adaptations in advance of the global trend. We show a persistent difference between the eastern and western sides of the Turkana Basin and suggest that the wetlands of the shallow eastern side could have provided additional humidity to the terrestrial ecosystems. Pending further research, a transient episode of faunal change centred at the time of the KBS Member (1.87–1.53 Ma), may be equally plausibly attributed to climate change or to a top-down ecological cascade initiated by the entry of technologically sophisticated humans.

This article is part of the themed issue ‘Major transitions in human evolution’.

No MeSH data available.