Double-decker dinosaur fossil find makes scientists rethink evolution of Jurassic giants
Scientists in Argentina have discovered the earliest-known "giant" dinosaur, revealing the evolution of gigantism began around 30 million years earlier than previously thought.
The dinosaur - named Ingentia prima, meaning "the first giant" - was the size of a double-decker bus, weighed about 10 tonnes, and lived around 210 million years ago during the Triassic Period.
The four-legged herbivore was three times the size of the next largest dinosaur species discovered from the Triassic period to date.
The find, published in the journal 'Nature Ecology & Evolution', has prompted paleontologists to rethink the evolution of dinosaurs.
"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 Cecilia Apaldetti, a paleontologist from the Universidad Nacional de San Juan in Argentina, and the study's lead author.
Ingentia prima was an early member of a dinosaur group called sauropods, a forerunner of the largest land animals that are known to have walked the Earth, including the Patagonian behemoths Argentinosaurus, Dreadnoughtus and Patagotitan.
Unlike later sauropods, Ingentia's legs were not pillar-like and its neck was shorter.
"We see in Ingentia prima the origin of gigantism, the first steps so that, more than 100 million years later, sauropods of up to 70 tonnes could come into existence like those that lived in Patagonia," Dr Apaldetti said.
For most dinosaurs, gigantism proved to be an evolutionary survival tool, especially among herbivores who could use their size as a form of defence against predators.
The fossil was found in the San Juan Province, in north-west Argentina, during a field trip. The region has been the site of previous discoveries of creatures such as ancient turtles and iguanas as well as other dinosaur species.
The scientists found four skeletons in all, one of the new Ingentia prima species and three of related dinosaurs.
It was at least twice as large as the other plant-eaters that shared the warm, savannah environment it inhabited. (© Daily Telegraph, London)