Soru

In paleoecology, reconstructing the chronology of Late Pleistocene megafaunal extinctions traditionally relied on radiocarbon dating of fossil bones, a method susceptible to the 'Signor-Lipps effect,' where the rarest, latest-surviving individuals are statistically unlikely to be fossilized, making extinctions appear earlier than they occurred. To circumvent this taphonomic bias, researchers increasingly analyze sediments for the spores of Sporormiella, an obligate dung-inhabiting fungus that reproduces on the fecal matter of large herbivores. Because Sporormiella spores deposit continuously in lake and mire sediments, a sharp decline in their relative abundance below an established threshold (typically 2 percent of total terrestrial pollen and spore counts) serves as an indirect indicator of herbivore population collapse. Crucially, in several northeastern North American sedimentary profiles, the Sporormiella decline precedes both the Younger Dryas climatic cooling and significant shifts in local pollen assemblages representing forest composition. This stratigraphic sequence suggests that the collapse of megafaunal biomass was neither triggered by the onset of abrupt cold conditions nor immediately preceded by a catastrophic depletion of the regional flora.

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