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Tracking late-Quaternary extinctions in interior Alaska using megaherbivore bone remains and dung fungal spores

Lookup NU author(s): Dr Maarten van Hardenbroek van AmmerstolORCiD



This is the authors' accepted manuscript of an article that has been published in its final definitive form by Cambridge University Press, 2020.

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One major challenge in the study of late-Quaternary extinctions (LQE) is providing better estimates of past megafauna abundance. To show how megaherbivore population size varied before and after the last extinctions in interior Alaska, we use both a database of radiocarbon-dated bone remains (spanning 25-0 ka) and spores of the obligate dung fungus, Sporormiella, recovered from radiocarbon-dated lake-sediment cores (spanning 17-0 ka). Bone fossils show that the last stage of the LQE in the region occurred at about 13 ka ago, but the number of megaherbivore bones remains high into the Holocene. Sporormiella abundance also remains high into the Holocene and does not decrease with major vegetation changes recorded by arboreal pollen percentages. At two sites, the interpretation of Sporormiella was enhanced by additional dung fungal spore types (e.g. Sordaria). In contrast to many sites where the last stage of the LQE is marked by a sharp decline in Sporormiella abundance, in interior Alaska our results indicate the continuance of megaherbivore abundance, albeit with a major taxonomic turnover (including Mammuthus and Equus extinction) from predominantly grazing to browsing dietary guilds. This new and robust evidence implies that regional LQE events were not systematically associated with crashes of overall megaherbivore abundance.

Publication metadata

Author(s): Conroy KJ, Baker AG, Jones VJ, van Hardenbroek M, Hopla EJ, Collier R, Lister AM, Edwards ME

Publication type: Article

Publication status: Published

Journal: Quaternary Research

Year: 2020

Volume: 97

Pages: 99-110

Print publication date: 01/09/2020

Online publication date: 28/04/2020

Acceptance date: 27/02/2020

Date deposited: 11/02/2020

ISSN (print): 0033-5894

ISSN (electronic): 1096-0287

Publisher: Cambridge University Press


DOI: 10.1017/qua.2020.19


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