The origin of the giant dinosaurs

Tipping the scales at around 10 tons – around two or three African elephants, say – Ingentia prima might have marked the point at which gigantism in dinosaurs first started, the researchers say, laying the biological groundwork for the huge sauropods (weighing up to 70 tons) that followed around 100 million years later.

With an elongated neck and tail, Ingentia prima could have grown to around 10 metres (33 fee ) in total, based on the bones discovered at the Balde de Leyes dig site in the San Juan province.

There is also some evidence in the fossil find for how the dinosaur might have been able to get so big so quickly. The team identified a bird-like breathing system that would let the animal keep reserves of oxygenated air, and cool down faster. The uncovered bones also show signs of separate growth spurts, whereas later sauropodomorphs increased in size much more gradually.

"The development of huge size wasn't just a one-off event for the sauropods, but rather different types of dinosaurs were able to become colossal, which speaks to just how incredible these animals were."

https://www.sciencealert.com/dinosaurs-grew-to-gigantic-sizes-way-earlier-than-we-thought