The Maxakalisaurus topai, of the Titanosauria group, was 13 metres long and weighed about nine tonnes.
It had a large body, long tail and neck with a relatively small head. Some of the bones found had the marks of teeth on them, which led scientists to believe that the specimen was devoured by carnivorous dinosaurs after its death.
The fossils date back to the Late Cretaceous period. They were found during excavations between 1998 and 2002 next to a highway in a place called Serra da Boa Vista in central-southern Minas Gerais state. It then took some time for the scientists to categorise the species and reconstruct the skeleton.
The name of the species, Maxakalisaurus topai, derives from an Indian tribe, Maxakali, which lives in the area. Topa is a divinity that the tribe worships. It is a custom in Brazil to give native Indian names to paleontological finds.
The find is extremely important as Maxakalisaurus topai is closely related to a highly evolved group of dinosaurs, called the Saltasaurinae, researcher Alexander Kellner said after presenting a reconstructed skeleton of the reptile in the National Museum in Rio de Janeiro.
The Saltasaurinae lived 70 million years ago and the fossils have only been found in Argentina.
"Among its specific traits are some peculiarities that we found in the vertebrae, especially a protuberating sacral vertebra ... It also has teeth with carinae (ridges), which we think served to better process the food," Kellner said.
Dinosaurs from the Titanosauria group were the main herbivorous dinosaurs of the ancient super-continent known as Gondwana, which grouped Australia, India, Africa, South America and Antarctica some 200 million years ago.
Some scientists believe a connection still existed between what is now South America, Antarctica, India and possibly Australia until about 70 million years ago.