A kitten-sized but formidable hunter preyed on animals of its size in Bolivia about 13 million years ago, researchers have found.
"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," said Russell Engelman of Case Western Reserve University in the US.
Analysis of a partial skull that had been in a University of Florida collection more than three decades showed that the predator is one of the smallest species reported in the extinct order Sparassodonta.
The researchers refrained from naming the new species mainly because the specimen lacks well-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.
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"Most predators do not go after animals of equal size, but these features indicate this small predator was a formidable hunter," said Darin Croft, an anatomy professor at Case Western Reserve University.
The findings appeared in the Journal of Vertebrate Paleontology.