Geological Society of America

T121 Exploring Changes in Climate, Flora, and Fauna of Africa through the Cenozoic

Monday, 16 October 2023
1:30 PM - 5:30 PM
321

NEOGENE ECOSYSTEMS AND MAMMAL DIETS IN EAST AFRICA

Paper number: T121-2
Program: Technical Sessions
Time: 1:45 PM – 2:00 PM

Authors

Kevin Uno Presenting Author
Harvard University, Cambridge, MA
Linet Sankau
Arizona State University, Tempe, AZ
Natasha Vitek
Stony Brook University, Stony Brook, NY
Daniel R. Green
Harvard University, Cambridge, MA
Sneha Bapana
Barnard College, New York, NY
Ashley House
Columbia University, New York, NY
Catherine Beck
Hamilton College, Clinton, NY
Cynthia M. Liutkus-Pierce
Appalachian State University, Boone, NC
Ellen Miller
Wake Forest University, Winston-Salem, NC
Patricia Princehouse
Case Western Reserve University, Cleveland, OH
John Rowan
University at Albany, Albany, NY

Abstract

Biomarker records from deep sea cores document dramatic terrestrial ecosystem change swept across much of Africa during the late Neogene (~10 Ma), when the primary spread of C₄ grasslands began, culminating in the modern savanna ecosystems that characterize much of sub-Saharan Africa today. Tooth enamel records from terrestrial archives in eastern Africa show that many large herbivores began to shift their diets towards C₄ vegetation (e.g., tropical grasses) at 10 Ma, concurrent with the primary spread of grassy ecosystems. Recent isotopic and phytolith data now suggest that C₄ vegetation was present prior to 10 Ma and as early as ~21 Ma in eastern Africa, which has major implications for our understanding of climatic drivers of vegetation change and the evolution of mammals, including primates and early humans.

A relatively understudied dimension of these early Neogene ecosystems is the diet of large herbivores. If C₄ vegetation comprised a significant proportion of early Neogene biomass, it is reasonable to assume herbivores would eat it. Here, we evaluate the diets of early Neogene large herbivores through stable isotope analysis of ~650 fossil teeth from seven fossil sites in the Turkana Basin ranging in age from 29 to ~5 Ma. We also compiled ~850 previously published enamel isotope data from other sites in Africa spanning 37 to 5 Ma. For samples older than 10 Ma, 98% indicate C₃-dominated diets with the remaining 2% of samples indicating possible minor amounts (up to ~10%) of C₄ vegetation in herbivore diets. We find no evidence of C₄-dominated diets. Overall, C₄ vegetation was likely present, consistent with previous results, but our results indicate it was not a significant proportion of large herbivore diets and its ecological significance requires additional evaluation. Furthermore, our new enamel isotope dataset enables finer scale investigations of dietary niche-partitioning, body water variations, and hydroclimate within and between fossil sites.

Geological Society of America Abstracts with Programs. Vol. 55, No. 6

doi: 10.1130/abs/2023AM-391622

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