Almost one million years ago, hypercarnivores roamed the Earth, feasting on prehistoric mammals like wooly mammoths and mastodons and keeping the planet’s ecosystems in check. According to a report from Discovery News, packs of these predators probably had an easy time taking down the large fauna that roamed the Earth during the Pleistocene era.

Recent computer models have simulated the killing power of ancient predators like the cave hyena or the saber-toothed tiger. These animals ate a diet solely of meat, and had to take down some pretty hefty prey animals to feed their packs.

The models show that these predators, which were also much larger than today’s wolves, hyenas, and lions, kept populations of large grazing animals in check.

According to the study’s head author, Blaire Van Valkenburgh, an evolutionary biologist at the University of California, Los Angeles, “The probable role these large predators played in maintaining stable ecosystems hasn’t been recognized until now.”

In the present day, large herbivores like elephants and deer can absolutely decimate an environment if their numbers are allowed to grow past a certain level. Grazers can strip entire fields and forests of edible vegetation. Ancient predators that fed on large grazing animals likely prevented massive environmental destruction from overgrazing during the Pleistocene era.

During this era, grazers weighing 1,760 pounds and up dominated the Earth, but had more natural predators to worry about than present-day elephants currently do. Since many of these ancient apex predators no longer have nay surviving lineages on Earth, it can be difficult to deduce what they may have eaten.

While the predators of the Pleistocene were much more diverse, there was more than enough prey for them to keep in check. Using information gleaned from the fossil record, the models paint a picture of the different trophic relationships during the and offer new insights into the history of predators on Earth.