PBS
Nova: America's Stone Age Explorers: End of the Big Beasts
Three opposing views about the disappearance of the "megafauna" in North America. What really happened to the wooly mammoth, mastadon, saber-toothed tiger, among other animals?
Bagheera
Bagheera.com: Extinct in the Wild Pleistocene Mammoth and Sabertooth Cat
This article is about the many mammals that became extinct in the late Pleistocene era. Many causes are considered and there are some great questions at the end for your consideration.