

Three tough mammals -- a huge "bear dog" and two saber-toothed cats -- were among Europe's top predators 9 million years ago, according to a new study.

The unusual toothy trio managed to coexist and thrive near what is now Madrid, Spain. The two cat species, lion-sized Machairodus aphanistus and the smaller leopard-sized Promegantereon ogygia, were in the same family Felidae as living big cats and domesticated housekitties.

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The prehistoric cats lived together in a woodland area and likely hunted the same species: horses and wild boar.

"The killing technique of these two saber-toothed cats is through a bite to the throat of the immobilized prey that produced a quick death due to the damage inflicted to blood vessels and trachea," study author Soledad Domingo told Discovery News. "These cats used their long, flattened upper canines to cut the throat of their prey in a head-depression movement in which the mandible served as an anchor."

The bear dog (Magericyon anceps), as its name suggests, looked half bear and half dog.


"In fact they were neither dogs nor bears, but in a group of their own," said Domingo, a postdoctoral fellow at the University of Michigan Museum of Paleontology, who added that the entire family of these carnivores went extinct. "The features of the teeth of Magericyon anceps indicate that this bear dog was able to crush bones."

It likely hunted antelopes.

Domingo and colleagues used a dentist's drill with a diamond bit to sample teeth from 69 specimens, including 27 saber-toothed cats and bear dogs. The rest were plant eaters.

They isolated carbon from the tooth enamel and measured the ratio of the more massive carbon 13 molecules to the less massive carbon 12. Both forms are present in the carbon dioxide that plants take in during photosynthesis. When an herbivore eats a plant, the plant leaves an isotopic signature in the animal's bones and teeth.

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"This would be the same in your tooth enamel today," Domingo explained. "If we sampled them, we could have an idea of what you eat. It's a signature that remains through time."

Although the saber-toothed cats went after the same prey, the researchers believe that the smaller species could have used tree cover to avoid encountering the larger cat. The bear dog hunted in a more open area that overlapped the cats' territory, but was slightly separated.

"By analogy with modern carnivorans, it is likely that encounters between carnivorans were aggressive and that they could have fought for prey or carcasses, however, it is not likely that these carnivorans had each other as common prey," Domingo said.

The toothy prehistoric trio lived during the late Miocene Period in a forested region that had patches of grassland. Today it's called Cerro de los Batallones.

Domingo, who has been excavating there for the past eight years, said two of its known nine fossil areas are ancient pits with an abundance of carnivore bones. Prey likely became trapped in the pits back in the day, leading to a feast for predators.

The findings, published in the latest Proceedings of the Royal Society B, demonstrate how timeless predator-prey relationships can be, since today's food webs are organized in a similar way.

Co-author Catherine Badgley explained, "Even though none of the species in this 9-million-year-old ecosystem are still alive today, we found evidence for similar ecological interactions as in modern ecosystems."

© 2012 Discovery Channel


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