The animal weighed between six and eight tonnes and measured 12.5 metres long. Its five-foot long head had massive jaws filled with sharp teeth.
Scientists have named it Giganotosaurus carolinii because of its large size and in honour of the Argentinian who found the specimen, Ruben Carolini. The carnivore lived about 97 million years ago, 30 million years before T rex.
Although the fossil bones were uncovered in August 1993 in Patagonia, the enormity of the find emerges only today with the first published details in the science journal Nature.
Rudolfo Coria, professor of natural science at the Carmen Funes Museum in Neuquen, said the teeth are typical of meat-eaters, with serrated edges and pointed tips. It is a member of the theropod family of dinosaurs, which includes its distant relative T rex.
Professor Coria said researchers have found about 70 per cent of Giganotosaurus's bones, enough to build up an accurate picture.
The biggest specimen of Tyrannosaurus rex, nicknamed ``Sue'', is just smaller than ``Caroline'', he said. The thigh bone of Caroline is 1.43 metres long, about 5 centimetres longer than that of Sue, which was found in South Dakota, Professor Coria said. ``Furthermore, the more robust bones of Giganotosaurus indicate that it was heavier than Tyrannosaurus.''
Angela Milner, a dinosaur expert at the Natural History Museum in London, said the discovery shows that large dinosaurs evolved separately in the northern hemisphere, where T rex lived, and the southern hemisphere.
Despite its size, Giganotosaurus, it is still smaller than the largest known predator - an ancient crocodile with a 2-metre head and a 20-metre body.Reuse content