Study Sheds Light on How Miocene Predators Shared Space and Food

An international team of paleontologists led by the University of Michigan has studied fossilized teeth of saber-toothed cats and bear dogs found at Cerro de los Batallones in Spain to reveal how the extinct predators shared space and prey during the late Miocene period some 9 million years ago.

This picture depicts how the region of Cerro de los Batallones in central Spain likely looked 9 million years ago (Mauricio Antón)

The paleontologists analyzed the tooth enamel of fossil teeth of a leopard-sized Promegantereon ogygia, lion-sized Machairodus aphanistus and a bear dog. The findings appear today in the Proceedings of the Royal Society B.

The team conducted what’s called a stable carbon isotope analysis on the animals’ teeth. Using a dentist’s drill with a diamond bit, they sampled teeth from 69 specimens, including plant-eaters and predators – 27 saber-toothed cats and bear dogs. They isolated the carbon from the tooth enamel and, using a mass spectrometer, measured the ratio of the more massive carbon 13 molecules to the less-massive carbon 12.

Carbon 12 and 13 are both present in the carbon dioxide that plants take in during photosynthesis. Different plants make use of the isotopes in different ways, and so they retain different amounts of them in their fibers. When an herbivore eats a plant, that plant leaves an isotopic signature in the animal’s bones and teeth. The signature travels through the food chain and can be found in carnivores as well.

“This would be the same in your tooth enamel today,” said lead author Dr Soledad Domingo of the University of Michigan’s Museum of Paleontology. “If we sampled them, we could have an idea of what you eat. It’s a signature that remains through time.”

Because the paleontologists can tell what the herbivores ate, they can surmise what their habitat was like. They found that cat species P. ogygia and M. aphanistus lived together in a woodland area. The predators likely hunted the same prey: horses and wild boar. In this habitat, the small saber-toothed cats could have used tree cover to avoid encountering the larger ones. Bear dogs likely hunted antelope in a more open area that overlapped the cats’ territory, but was slightly separated.

“These three animals were sympatric – they inhabited the same geographic area at the same time. What they did to coexist was to avoid each other and partition the resources,” Dr Domingo explained.

“The three largest mammalian predators captured prey in different portions of the habitat, as do coexisting large predators today. So 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,” said study co-author Prof Catherine Badgley of the University of Michigan’s Museum of Paleontology.

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Bibliographic information: M. Soledad Domingo et al. Resource partitioning among top predators in a Miocene food web. Proc. R. Soc. B, published online before print November 7, 2012, doi: 10.1098/rspb.2012.2138