Scientists called it a new species, 'Guarinisuchus munizi,' and said it sheds new light on the evolutionary history of modern crocodiles.

The fossil includes a skull, jaw bone and vertebrae, making it one of the most complete examples of marine corcodylomorphs collected so far in South America, said Mr Alexander Kellner of the National Museum of the Federal University of Rio de Janeiro. He and other scientists unveiled fossils and a model of the 3-metre-long crocodile at the museum.

'It's a very rare find and it gives rise to several new theories,' said Mr Kellner, who co-authored an article on the find that was published on Tuesday in Proceedings of The Royal Society B, a London-based peer-reviewed journal.

Guarinisuchus appears to be closely related to marine crocodylmorphs found in Africa, which supports the hypothesis that the group originated in Africa and migrated to South America before spreading into the waters off the North American coast, Mr Kellner said.

The find also suggests that marine crocodylmorphs replaced marine lizards during the early Paleocene era, about 65 million years ago - the same time marine lizards became extinct. They believe it's a new species based on anatomical differences in the skull that are unique to this creature.

Prof Philip Currie, a palaeontology professor at the University of Alberta, Canada who was not involved with the discovery, said it was an important find.

'There are a lot of unknowns with this group in terms of evolution. Clearly the discovery of a specimen as nice as this one will help sort things out,' Prof Currie said in telephone interview.

The bones were found in the northeastern state of Pernambuco.

Scientists named the species 'Guarinisuchus' after the Tupi Indian word 'Guarani,' which means warrior and 'munizi,' in honor of Brazilian palaeontologist Deraldo da Costa Barros Muniz, who has discovered many dinosaur fossils off Brazil's northeastern coast. Prof Muniz did not participate in this find.

Scientists have discovered a wealth of crocodile ancestors around Brazil in recent years.

In January, they announced the discovery of an 80 million-year-old land-bound reptile described as a possible link between prehistoric and modern-day crocodiles.

Two years ago, paleontologists from the Federal University of Rio de Janeiro announced the discovery of a 70-million-year-old crocodile fossil that they called Uberabasuchus Terrificus, or 'Terrible Crocodile of Uberaba.' -- AP