LIMA, May 25 (Reuters) - The nearly intact fossil of an ancient sloth that lived 5 million years ago has been unearthed in Peru, a find about 4 million years older than similar ones discovered in the Americas, researchers said.

The sloth was found beneath the cement floor of a house in the Andean region of Espinar in southern Peru when workers were installing a water system. Parts of a giant armadillo that has also been dated to 5 million years ago were also found nearby.

The sloth, about 10 feet (3 metres) long, was an herbivore and lived during the Mio-Pliocene era, said paleontologist Rodolfo Salas of Peru's Natural History Museum and one of the scientists on the dig sponsored by the French government.

"This skeleton of the sloth is especially important as it is the first complete skeleton of its kind that is 5 million years old in the Americas," he told Reuters.

"Previously, discoveries have been made of partial skeletons of similar animals, but from the Pleistocene era, meaning from the last million years."

The sloth was found at 13,000 feet (4,000 metres) above sea level.

Salas said the sloth was relatively small compared with other animals of its type and would help researchers better understand evolution of mammals in the Andes.

Peru's dry climate has helped preserve thousands of fossils from the Pacific coast to the Andes highlands, making it a favorite of fossil hunters.

(Reporting by Carlos Valdez; Writing by Terry Wade; Editing by Peter Cooney)