Study: 'Hypercarnivores' kept ancient herbivores in check

DURHAM, N.C., Oct. 27 (UPI) -- During the last ice age, as recently as 15,000 years ago, everything was like it is in Texas -- bigger.

Herding herbivores were especially large, both in size and number. So how did the Earth survive, with all these hungry grazers plowing across the land? It's simple -- carnivores were bigger too.

In a recent study, researchers at Duke looked at how big Pleistocene predators were and what that would have meant for their hunting abilities.

Columbian mammoths, mastodons and giant ground sloths would have faced hyenas and sabertooth tigers roughly twice the size of today's wolves and lions. Researchers used math models to determine the upper limits of the prey these so-called hypercarnivores could conceivably target.

Their results -- published in the journal PNAS -- suggest a large cave hyena could have successfully taken down a juvenile mammoth weighing up to a ton. If predators hunted in packs, as hyenas and some lions do today, hypercarnivores could have successfully targeted mammoths weighing up to two tons.

"From the present day, it seems that big animals like elephants are immune to predation," Duke biologist V. Louise Roth said in a press release. "In fact, Pleistocene ecosystems were a lot more complex and predators could have had a larger impact."

Roth and lead study author, UCLA paleoecologist Blaire Van Valkenburgh, say the fossil record doesn't reflect the true size of hypercarnivores. Humans, they argue, would have targeted the largest predators over time. The fossil record from the Pleistocene era focuses on the last few hundred years of the last ice age.