Prehistoric guinea pig was largest rodent on Earth

Standing as tall as a horse and as powerful as an ox, it cut a fearsome figure as it roamed the banks of an ancient Venezuelan river.

Standing as tall as a horse and with the power of an ox, it cut a fearsome figure as it roamed the banks of an ancient Venezuelan river.

But its modern-day counterpart is more likely to be found living a life of domestic harmony in a cage in the sitting room.

Scientists reveal today in the journal Science that the guinea pig has shrunk from being the largest rodent that ever lived to a pint-sized furry friend of children over.

"Imagine a weird guinea pig, but huge, with a long tail for balancing on its hind legs and continuously growing teeth," said Marcelo Sanchez-Villagra, one of the team of researchers at the University of Tubingen in Germany.

The giant rodent roamed the banks of an ancient Venezuelan river eight million years ago, munching sea grass and avoiding crocodiles, in a lush tropical landscape.

Analysis of a fossil skeleton found at Urumaco, 250 miles west of Caracas, showed it to be the evolutionary sibling of modern-day guinea pigs.

The team called the animal, formally known as the Phoberomys pattersoni, "Goya" ­ though a more appropriate name might have been "Guineazilla". Much like the guinea pig, its hindquarters and rear legs were far more powerful than its forelimbs. Unlike its relatives today, phoberomys had a long tail, which was thought to be used for balancing upright on its hind legs.

The largest rodent alive now is the capybara, which like "Goya" is semi-aquatic and lives in South America ­ but only weighs up to 100lb (45kg) and is two feet tall.

The British zoologist Professor R McNeill Alexander, from the University of Leeds, said that the animal became extinct because it couldn't run and it couldn't hide.

"Small mammals commonly escape predators by retiring into a refuge such as a burrow," he said. Predators were able to catch it too easily for the species to survive.

That it was able to grow so large at all was probably due to South America having been an island for tens of millions of years, said Andrew Sugden, an evolutionary biology expert and international managing editor of Science. The emergence of a land bridge connected it to Central America about three million years ago.