Nearly a million years ago, a cave hyena could have taken down a 5-year-old mastodon weighing more than a ton. And in packs, the predators may have been equipped to demolish a 9-year-old mastodon weighing a hefty 2 tons.
That's according to new computer models that can calculate how big a target an ancient hypercarnivore, such as the cave hyena and the saber-toothed cat that rely solely on meat for sustenance, might have tackled, researchers say.
These findings show how ancient super-predators far larger than the wolves, lions and hyenas of today once kept megaherbivores such as mammoths, mastodons and giant ground sloths in check, researchers said. [Photos: Autopsy of a 40,000-Year-Old Mammoth]
"The probable role these large predators played in maintaining stable ecosystems hasn't been recognized until now," said the study's lead author, Blaire Van Valkenburgh, an evolutionary biologist at the University of California, Los Angeles.
Nowadays large herbivores such as elephants and white-tailed deer can have devastating effects on the environment by stripping it of vegetation through overgrazing (eating ground plants) or overbrowsing (eating leaves off trees). This brings up the question of what prevented widespread habitat destruction in the Pleistocene epoch, which lasted from about 1 million to 11,000 years ago. Back then, a much greater diversity of megaherbivores - plant-eaters 1,760 lbs. (800 kilograms) and larger - roamed the Earth.
Modern research suggests that current megaherbivores like elephants are largely immune to predators. However, scientists now find that ancient hypercarnivores had the ability to, and likely did, limit megaherbivore numbers.
The impact of ancient hypercarnivores on past megaherbivores may have been difficult to appreciate because many extinct hypercarnivores such as saber-toothed cats have no close living counterparts, the researchers noted. This makes it difficult to deduce what they might have preyed on.
Still, the researchers noted there was once a much greater diversity of predators than exists today, many of which were significantly larger than their modern analogs - for the ones that do have analogs. This diversity suggests there was once intense competition between these carnivores, perhaps leading some to specialize in hunting megaherbivores.
To deduce the potential impact of ancient hypercarnivores, the researchers analyzed the fossil record to gauge size ranges for Pleistocene predators larger than about 45 lbs. (21 kg). Whereas modern hypercarnivores average 116 to 138 lbs. (53 to 63 kg), fossil hypercarnivores spanned 211 to 297 lbs. (96 to 135 kg) on average.