People have tried to avoid the likelihood that humans were directly responsible for killing off the large mammals in the Americas by suggesting the cause was a lack of food due to changing climate. But humans habitually kill off other species, esp. those that compete with or hunt us.http://www.eurekalert.org/pub_releases/2012-12/vu-eci121812.php
Public release date: 26-Dec-2012
Contact: David Salisbury
Vanderbilt University
In the period just before they went extinct, the American lions and saber-toothed cats that roamed North America in the late Pleistocene were living well off the fat of the land.
That is the conclusion of the latest study of the microscopic wear patterns on the teeth of these great cats recovered from the La Brea tar pits in southern California. Contrary to previous studies, the analysis did not find any indications that the giant carnivores were having increased trouble finding prey in the period before they went extinct 12,000 years ago.
The results, published on Dec. 26 in the scientific journal PLOS ONE, contradicts previous dental studies and presents a problem for the most popular explanations for the Megafaunal (or Quaternary) extinction when the great cats, mammoths and a number of the largest mammals that existed around the world disappeared.
"The popular theory for the Megafaunal extinction is that either the changing climate at the end of the last Ice Age or human activity – or some combination of the two – killed off most of the large mammals," said Larisa DeSantis, assistant professor of earth and environmental sciences at Vanderbilt, who headed the study.
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