Timeline of atmospheric CO₂ evolution (IMAGE)
Caption
Timeline of atmospheric CO₂ evolution, faunal turnover, and topographic uplift during the Miocene, providing a contextual framework for interpreting
ecological and climate model results. (A) Reconstructed atmospheric cO₂ concentrations from the late Oligocene to the late Miocene, compiled from 32 published
proxy records that are indicated by different colors. the gray band represents the lOeSS- smoothed average, with the Miocene climate optimum (McO), Middle Miocene
climate transition (MMct), and late Miocene cooling (lMc) highlighted. colored points represent individual data series. this trajectory illustrates the transition from a
high-cO₂ world (>600 ppm) to substantially lower concentrations (~300 ppm) after the MMct. (B) timeline of selected African carnivore species ranges during the Middle
Miocene, illustrating turnover associated with the MMct. taxa shown (e.g., Afrosmilus, Ginsburgsmilus, and Barbourofelis) represent faunal elements that appear or go
extinct near this interval, based on biostratigraphic data compiled from Werdelin (19) and others. the red vertical band denotes the timing of the MMct (ca. 14.5–13.5 Ma),
emphasizing its temporal overlap with carnivore community restructuring. (C) Paleotopographic reconstructions of African elevation at 25, 20, and 15 Ma, relative to
present-day conditions, based on dynamic topography model output from Moucha and Forte (10). Blue shading indicates regions lower than present; red shows uplifted
areas. these maps capture the progressive development of the east African Rift System (eARS) and ethiopian highlands, which played a critical role in reshaping African
hydroclimate and ecosystems. Key evolutionary events along the timeline (e.g., crown hominoid emergence, early c₄ grass expansion) are included for orientation.
Credit
Niklas Werner and Qiong Zhang.
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