Dinosaur fossils found in Patagonia provide the first evidence that long-necked, whip-tailed diplodocid sauropods survived well beyond the Jurassic period, when they were thought to have gone extinct, according to Argentine paleontologists.

Scientists announced the discovery of the fossilized remains of a plant-munching dinosaur from the sauropod group, the largest known land creatures in Earth's history. The fossils indicate the largest dinosaur ever found.

The diplodocid fossils also are the first of their kind found in South America. The creature lived about 140 million years ago, millions of years after scientists previously thought diplodocids had disappeared, according to Argentine paleontologist Pablo Gallina, one of the researchers.

"It was a surprise because the first remains we found were very deteriorated and we didn't think much of them, but later through careful laboratory work, cleaning rock from the bones, we could see that they were from a diplodocid, something unthinkable for South America,” he said.

Gallina's team says the fossils show that diplodocids roamed South America during the early Cretaceous period, well after scientists thought these kinds of dinosaurs became extinct. They also suggest that the diplodocid clade, or family group, evolved from other dinosaurs before the Earth's continents split apart, which is earlier than previously thought.

Explaining the find a day after the conclusions were published in the PLOS One scientific journal, the scientists said the eight vertebrae they recovered belong to a new species they named Leinkupal laticauda. That's a combination of Mapuche words meaning "vanishing" and "family" and Latin for "wide" and "tail."

The dinosaur weighed about 80 tons, the equivalent of 14 adult bull African elephants, according to The Guardian newspaper.

"It's like two trucks with a trailer each, one in front of the other, and the weight of 14 elephants together," José Luis Carballido, the Argentinian paleontologist who led the dig, told the newspaper. "This is a real paleontological treasure. There are plenty of remains, and many were nearly intact, which is unusual."

The remains were found in rocky outcrops of the Bajada Colorada, a Cretaceous formation south of the town of Picun Leufu in Neuquen province.

Paleobiologist Paul Upchurch, a sauropod expert at University College London who was not involved in the study, said it suggests that not all diplodocids succumbed to a mass extinction about 140 million years ago at the end of the Jurassic period.

"Here's evidence that one or two groups got through, rather than a total extinction, that it was devastating, but it didn't completely kill them off," Upchurch said.

As for the conclusion that the South American find shows diplodocids evolved from a common ancestor earlier than previously thought, Upchurch said, "There's certainly a possibility that this would push the origin back a bit," given that Africa and South America separated during the Jurassic period.

Another expert, paleontologist John Whitlock of Mount Aloysius College in Pennsylvania, also lauded the finding.

"A discovery like this is more than just another data point. It's a chance to re-evaluate our understanding of how the group spread across the globe through time," he said.

"We can use that information to do things like examine how dinosaurs might have chased their preferred environment around the globe as the climate changed, and that's the sort of research with direct implications for those of us around today."

Al Jazeera and wire services