BUENOS AIRES (REUTERS) - These are the fossilised remains of one of the last giants to roam the earth.

The Nullotitan glaciaris is a newly discovered species of dinosaur, according to scientists in Argentina.

They discovered the fossils in the southern Patagonia area of the country known for its barren deserts and ice fields.

"These discoveries are from a new archaeological site that is full of plant fossils, dinosaur fossils and other vertebrae," said paleontologist Fernando Novas. "It has revealed an ecosystem from around 70 millions of years ago, before dinosaurs became extinct."

But before they all died off, the scientists say, the Nullotitan was very common in the region, judging from the number of fossils they found at the site.

They also learnt their new discovery was massive.

"It was 25m long," said Novas. "It was an herbivore, with a long neck and four legs."

Scientists also discovered a smaller herbivore species: the Isasicursor santacrucensis.

"The interesting thing about this discovery was that we found many bones, adults and youth, all mixed together," said Novas. "This is one of the few discoveries that reveal to us that these dinosaurs species lived in groups, in packs."

That behavior, they said, helped protect them against other species which preferred meat over vegetation.