Scientists in Brazil say a fossil of an elephant's tooth found in the Amazon jungle proves the presence of pachyderms in South America some 45,000 years ago, a report said on Tuesday.

"Only elephants and capybaras (large rodents) have teeth with this kind of laminate structure, but those of capybaras are no longer than five centimeters (two inches)," while the fossil measured 12 centimeters, said Mario Cozzuol in the daily Folha de Sao Paulo.

Previous evidence showed that had reached Costa Rica, in Central America, but no further south, said the expert from the Federal University of Minas Gerais.

The was discovered at the start of the 1990s by a precious metals researcher, but a university student only noticed its laminate structure years later.