Sabre-toothed cats and other large carnivores were probably able to hunt down young mammoths and mastodons during the Pleistocene epoch, between 2.6 million years and 12,000 years ago. That would explain why Earth's forests were not grazed to death by the large numbers of big herbivores before they went extinct.

Researchers have long thought that mammoths and other giant herbivores were too large to have predators. Blaire Van Valkenburgh of the University of California, Los Angeles, and her colleagues analysed data on the relative body masses of modern predators and prey, and compared them with those of fossil specimens. They estimate that some Pleistocene predators, such as sabre-toothed cats and very large hyenas, were big enough to kill young megaherbivores — enabling them to control herbivore populations.

Proc. Natl Acad. Sci. USA http://doi.org/8th (2015)