A team of researchers from the University of California, Los Angeles (UCLA) analyzed teeth fossils from ancient predators to see what they preyed on during the Pleistocene epoch. The team found that hypercarnivores such as cave hyenas and saber-toothed cats preyed on megaherbivores that led to the latter's declining numbers.

A cave hyena can devour a one-ton, five-year-old mastodon while a pack can demolish a two-ton, nine-year-old counterpart. These estimates come from a research that analyzed how ancient hypercarnivores such as the saber-toothed cat and cave hyena, also known as the Ice Age spotted hyena, hunted for meat. The research also looked into the size of meat sources these hyper carnivores devoured during that time.

The study findings give humans a glimpse into how these super predators kept megaherbivores at bay which could have wiped out natural habitat because they feasted on leaves of trees and ground plants.

"The probable role these large predators played in maintaining stable ecosystems hasn't been recognized until now," said lead author and evolutionary biologist Blaire Van Valkenburgh from University of California, Los Angeles (UCLA).

In today's modern world, herbivores like the white-tailed deer and elephants can destroy vegetation simply by eating leaves from tall trees (overbrowsing) or those that are ground level (overgrazing). Scientists have often wondered what kept their ancient brothers and cousins, the megaherbivores, from destroying the environment during the Pleistocene epoch, roughly one million to 11,000 years ago when they roamed more freely and with such massive weights. The researchers found that ancient hypercarnivores played a role in limiting the megaherbivore population.

Findings showed that ancient times had a wider variety of predators, most of which were more massive compared to their modern counterparts like the wolves and tigers. The presence of such diversity suggests that the ancient predators competed for meat supply and this problem perhaps led some to hunt on megaherbivores.

Using teeth fossils of Pleistocene predators, the researchers were able to develop size estimates of the animals. For the megaherbivores, the scientists used the ratio of shoulder height to body mass to compute for estimated sizes using mathematical formulas. These estimates enabled the team to decipher what ancient predators preyed on and how massive they were. The team concluded that massive herbivores such as mammoths and mastodons could have been hunted down by a pack of ancient hypercarnivores. Even among ancient mammals, the David and Goliath logic holds true and ancient predators also believed that there is safety in numbers.

The hypercarnivore pack theory can be explained by the evidence of broken teeth. When there is competition for food, predators eat more bone to make the most out of the carcasses.

The research was published in the Proceedings of the National Academy of Sciences journal on Oct. 26.