A team of paleontologists have showed reporters skulls of a rat-like mammal that lived when dinosaurs still roamed the earth and was recently discovered in southern Argentina.

The creature, one of the few mammals discovered in South America from the time of the dinosaurs, was between 10 and 14 centimetres long, had a thin snout and unusually long tusks.

The paleontologists also showed reporters a model of the mammal, baptised Cronopio dentiacutus, which looks surprisingly like the rat-like mammal Scrat from the animated Hollywood Ice Age movies.

Cronopio lived some 93 million years ago in the late Cretaceous Period (144 to 65 million years ago), the experts said.

“During the time of the dinosaurs no mammal was larger than a mouse,” said Sebastian Apesteguia, one of the three scientists who made the discovery, in a presentation at the Maimonides University in Buenos Aires.

The tiny mammals “could do whatever they wanted, but only underground or at night, but not in the view of dinosaurs,” said Dr Apesteguia, a researcher at the university’s National ­Council of Science and Technology.

The find includes two partial skulls and jaws of the ancient creature, showing dental and cranial features.

Dr Apesteguia made the discovery along with his colleagues Leandro Gaetano and Guillermo Rougier in a fossil deposit in the southern province of Rio Negro known as La Buitrera (Vulture’s Lair).

Fossils discovered at the site include a rooster-sized dinosaur related to the Velociraptor of “Jurassic Park” fame known as the Buitreraptor.

A detailed report on the find appears in the current issue of the journal Nature.

Dr Gaetano told reporters that Cronopio is related to a group of extinct mammals known as dryolestoids, the ancestors of modern marsupials and placental mammals.

Dryolestoid remains from ­earlier periods have been found in North America and Europe, but never in South America.