This new analysis would mean that titanosaurs, a diverse group of long-necked, plant-eating dinosaurs, lived longer ago than previously thought.
“The main importance of this fossil, apart from being a new species of titanosaur, is that it is the oldest recorded for this group worldwide,” Pablo Gallina of the National Scientific and Technical Research Council (Conicet) said.
He added that 140 million-year-old fossils are “really very scarce”.
The specimen, discovered seven years ago in Neuquén Province, northwest Patagonia, has been named ‘Ninjatitan zapatai’ after palaeontologist Sebastian ‘El Ninja’ Apesteguia and technician Rogelio Zapata.
As well as being the oldest titanosaur ever discovered, it is also believed to be the largest.
Although the fossil is incomplete, its pelvic bone and vertebrae suggest that the Ninjatitan zapatai was around 20 metres long. Its close relative, the Andesaurus, grew to be 18 metres long.
The largest animal to have ever existed remains the blue whale, however, which can grow to 33.5m long.
Titanosaurs were still roaming the earth when dinosaurs became extinct at the end of the Cretaceous period around 65 million years ago.