All remains except one Early Pleistocene partial skeleton from the Leisey Shell Pit near Charlotte Harbor, Florida (which may represent a different species or a subspecies) date from the Late Pleistocene, with the youngest remains dating from the Pleistocene-Holocene boundary.
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The species probably became extinct as the climatic shifts at the end of the last ice age led to widespread ecological alterations and prey scarcity, exacerbated by human hunting and increasing influence on habitat; generally, most large land animals disappeared and the altered precipitation patterns seriously affected populations of aquatic vertebrates.