However, the earliest examples of this group were small, bipedal creatures.
Recently-unearthed fossils in Argentina suggest that giant dinosaurs roamed the Earth some 30 million years earlier than scientists had previously thought.
According to scientists, Ingenia prima was the first dinosaur species to reach gigantism and even though it was a long way from the 70 tonnes (tons) that the biggest sauropods weighed from the end of the Cretaceous period (145-66 million years ago), the speed of bone tissue accumulation was greater than that of species from its era and the biggest giants that lived in Patagonia, in the south of Argentina.
"Although the origin of gigantism in sauropodomorphs [sauropods] was a pivotal stage in the history of dinosaurs, an incomplete fossil record obscures details of this crucial evolutionary change", the authors wrote in the study. To turn into towering behemoths, it was believed the development of straight legs for support and continuous, rapid growth were essential.
Ingentia Prima would have lived in what is now Argentina, but was then the southeast corner of the supercontinent Pangaea.
Its size would also have put it at less risk of being eaten by the many flesh eating dinosaurs that were already around. It was discovered in the Balde de Leyes dig site in San Juan province, 1,100km west of the Argentine capital Buenos Aires.
Dr Apaldetti said: 'Gigantism is an evolutionary survival strategy, especially for herbivorous animals'.
It's believed that the species grew to eight to 10 meters tall - the specimen found was a growing youth measuring six to seven meters - and weighed around 10 tonnes, equal to two or three African elephants.
Like later sauropods, lessemsaurids had elongated necks and tails, as well as air sacs resembling those that are found in birds.
'In addition, this kind of breathing implied the presence of cavities, or deep holes, in their bones - known as a pneumatic skeleton - that lightened the weight and would have favoured a large body size'.
But unlike their more recent counterparts they stood on bent legs and had bones that grew thick through accelerated bursts. It belongs to a group of dinosaurs known as sauropods, which includes some of the largest land animals ever known to have existed.