Scientists in Argentina have discovered the earliest-known "giant" dinosaur, revealing the evolution of gigantism began around 30 million years earlier than previously thought.

The dinosaur - named Ingentia prima, meaning "the first giant" - was up to 33ft long and weighed about 10 tons, living about 210 million years ago during the Triassic Period.

The four-legged herbivore is three times the size of the largest dinosaur species discovered from the Triassic period to date.

The find, published in the journal Nature Ecology & Evolution, has prompted paleontologists to rethink the evolution of dinosaurs.

"Before this discovery, gigantism was considered to have emerged during the Jurassic period, approximately 180 million years ago, but Ingentia prima lived at the end of the Triassic, between 210 and 205 million years ago,” said paleontologist Cecilia Apaldetti of the Universidad Nacional de San Juan in Argentina, the study's lead author.