The study from the University of Wisconsin, Madison, suggests the decline of mammoths, mastodons and other large ice age animals was a gradual process that took about 1,000 years, graduate student Jacquelyn Gill said in a release Thursday.
Gill and her team studied Sporormiella fungal spores in mammoth dung found in sediment deep within the bed of Appleman Lake in Indiana.
The declining number of spores presents a picture of how the animals roamed 15,000 years ago and disappeared over time, emptying a land rich with large animals, including camels, horses, ground sloths and giant beavers.
Broadleaved trees kept in check by the herbivores then took over the landscape, bringing an accumulation of woody debris and a dramatic increase in wildfires, which shaped the landscape, Gill's team said in a story published in the journal Science.
Ohio bar shooting arrested, charged with murder
LGBT community has 'bullied the American people': Bachmann