Anthropology Fall 2024 Colloquium Speaker Series

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 Alexandra Norwood, Ph.D.

 

"A seasonal-scale approach to megafaunal extinction"

 

Thursday, October 3, 2024

 

 

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*Seating is limited

"A seasonal-scale approach to megafaunal extinction"

Abstract:

The catastrophic extinction of Earth’s megafauna (animals > 45 kg) over the past 50,000 years has profoundly altered terrestrial ecosystems, but the drivers of these losses in Africa are understudied. In southern Africa, which provides the most detailed fossil record of these extinctions on the continent, changes in rainfall seasonality (the timing and amount of rainfall across the year) are hypothesized to have contributed to the disappearance of several large-bodied herbivores ~12,000 years ago. However, seasonality is notoriously difficult to reconstruct from the fossil record, so these hypotheses have been challenging to test. This talk will address these methodological challenges and the broader question of late Quaternary extinction in three parts. First, I will present an analysis of bulk ungulate enamel isotope data from sites that span the Pleistocene/Holocene transition and highlight both the complexity of controls on vegetation and faunal distributions across the distinct climatic regimes that divide southern Africa and the limitations of the existing stable isotope record to resolve paleoclimatic questions. Second, I will discuss additional inconsistencies between paleoenvironmental proxies during this time interval that implicate changing seasonality as a driver of ecosystem change. Lastly, I will outline my research agenda for my postdoc, which develops enamel serial sampling methodology for tracking seasonality in fossil ungulate teeth and then generates enamel isotope data to reconstruct changes in seasonality across the Pleistocene-Holocene transition in southern Africa.