dinosaur named Ingentia
© Cecilia ApaldettiThe new fossils belonged to a dinosaur that has been named Ingentia
Diplodocus is the largest creature to have walked, but not much is known about how it evolved such proportions. A new fossil challenges current ideas about the path to giant dinosaurs.

Cecilia Apaldetti and her colleagues at the National University of San Juan, Argentina, discovered a previously unknown dinosaur in north-west Argentina within a formation that dates to the late Triassic, around 220 million years ago. The researchers have christened it Ingentia prima, and placed it in a group of early sauropodomorphs called the lessemsaurids.

The lessemsaurids are distant relatives of giant sauropods like Diplodocus, and developed into giants around 50 million years before Dipolodocus. Although nowhere near as big as the 50-tonne Dipolodocus, Ingentia, short-necked and walking on two legs, still weighed up to 10 tonnes.

Diplodocus dinosaur
The massive dinosaur is giving us new clues about how they evolve.
"Until now we thought that to acquire gigantic size, it was necessary to acquire adaptations in the structure of the skeleton to support this weight," says Apaldetti's colleague Ricardo Martínez. However, Ingentia lacks many of these - for example, it doesn't have the stout, columnar legs of Diplodocus and modern-day giants like elephants. Also, while giant sauropods grew continuously, tree-ring like patterns in the bone show lessensaurids had growth spurts.

Ingentia also developed bird-like air sacs that allowed it to breathe continuously - an important feature giant dinosaurs needed to get rid of their immense body heat.