A student at Case Western Reserve University in Ohio and his mentor discovered a predator the size of a kitten that lived in Bolivia 13 million years ago, the institution said.
This is one of the smallest specimens ever found of the Sparassodonta order, an extinct group of carnivorous mammals that was one of the principal predator species in South America during the Cenozoic Era.
Student Russell Engelman and anatomy professor Darin Croft made the discovery when analyzing a skull fragment that had been kept for more than 30 years in a collection at the University of Florida.
The specimen was found in a mountainous region known as Quebrada Honda in Bolivia in 1978, amid geological strata dating back between 12 million and 13 million years, but was never studied in detail until now.
The fragment was provisionally identified at the time as belonging to a group of extinct carnivorous opossums, partly because of its size, but Croft wanted to study it in depth because the age assigned it was almost double that of the oldest previously known species of flesh-eating opossum.
According to the researchers, the specimen “does not clearly correspond to any major sparassodont group…and represents a morphotype previously unknown among the Sparassodonta,” so for the moment it has not been given a name.
The skull, which complete would have measured 7 centimeters (2 3/4 inches) long, shows that the animal had a very small snout.
Moreover, a socket in the upper jaw indicates that it had large canine teeth that were round in cross-section, very similar to those of a meat-eating marsupial called the spotted-tailed quoll, or, incorrectly, the tiger cat, that lives in Australia today.
Sparassodonts were closer to present-day opossums than to cats or dogs, and the group includes some saber-toothed species which were therefore capable of feeding on larger prey.