Extinct 'kitten-sized' hunter that walked Earth 13 million years ago discovered

Researchers have discovered an ancient kitten-sized predator that lived in Bolivia about 13 million years ago - one of the smallest species reported in the extinct order Sparassodonta.

Third-year undergraduate student Russell Engelman and Case Western Reserve anatomy professor Darin Croft made the finding by analyzing a partial skull that had been in a University of Florida collection more than three decades.

Engelman, an evolutionary biology major from Russell Township, Ohio, said the animal would have been about the size of a marten, a catlike weasel found in the Northeastern United States and Canada, and probably filled the same ecological niche.

The researchers refrained from naming the new species mainly because the specimen lackswell-preserved teeth, which are the only parts preserved in many of its close relatives.

The skull, which would have been a little less than 3 inches long if complete, shows the animal had a very short snout.

A socket, or alveolus, in the upper jaw shows it had large, canines, that were round in cross-section much like those of a meat-eating marsupial, called the spotted-tailed quoll, found in Australia today, the researchers said.

Although sparassodonts are more closely related to modern opossums than cats and dogs, the group included saber-toothed species that fed on large prey. This small Bolivian species probably fed on the ancient relatives of today's guinea pigs and spiny rats, the researchers said.

The specimen was found in a mountainous site known as Quebrada Honda, Bolivia, in 1978, in rock layers dated 12 million to 13 million years ago.

Structurally, extinct meat-eating opossums and sparassodont skulls share a number of similarities due to their similar meat-eating diet, Engelman said.

The findings have been published online in the Journal of Vertebrate Paleontology.