Unlike later sauropods, Ingentia's legs were not pillar-like and its neck was shorter. But dinosaurs weren't always giants - during the earlier Triassic period they were mostly chicken-sized critters, and they didn't really grow to be massive until the Jurassic.
According to the researchers, the giant dinosaur bones belonged to big herbivore dinosaurs possessing long necks and tails, possibly belonging to the sauropods group.
Ingentia prima, which means "the first to be huge" in Latin, lived some 237 million to 201 million years ago in what is now Argentina.
"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. Their distant ancestors were small, agile, two-legged dinosaurs known as prosauropods.
"These pneumatic cavities indicate that this new species had highly developed air sacs and a very efficient breathing system, similar to what happens in modern birds, which also helped it to keep its body cool despite its large size".
"When we found the first remains of this dinosaur, we realized he was unique". Unlike the younger sauropods, these creatures stood on bent legs and had bones that thickened through accelerated bursts instead of steady and rapid growth.
Researchers in Argentina have discovered what they say is the oldest-known giant dinosaur and it's altering the way paleontologists view the evolution of dinosaurs as a whole.
'But with this discovery we can see the first steps toward gigantism occurred 30 million years before the giants dominated practically the entire planet'. Called the Ingenia prima, this dinosaur was thrice the dimensions of the bulkiest of Triassic dinosaurs.
Her group's investigations show that there is more than one way to super-size a dinosaur.
Scientists also suggested that there might be even bigger and stranger dinosaurs to be discovered. This way of growing was widespread amongst the dinosaurs of that era, but excluding Ingentia prima, no other species reached more than three meters in length while weighting around 1.8 tones.
The last, iconic sauropods had the benefit of a long history of evolutionary innovation in this regard, said Dr Apaldetti.