Giant dinosaurs lived on Earth nearly 30 million years earlier than previously thought, according to a team of paleontologists in Argentina, who unearthed fossils of the earliest-known giant dinosaur.
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.
Now, the discovery of Ingentia prima - a member of the Lessemsaurid group of dinosaurs and an ancestor of sauropods - shows that some dinosaurs had acquired several key characteristics during the Late Triassic that paved the way toward gigantism.
"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 tons could come into existence like those that lived in Patagonia", Apaldetti said.
Ingentia Prima, which was found alongside the remains of three individuals belonging to the already known species Lessemsaurus sauropoides, changes this.
Analysis showed that I. prima weighed between seven and 10 tonnes (the largest African elephants weight between six and seven tonnes), and it already exhibited an elongated neck and long tail, though not almost as pronounced as those seen later. The first ones were modestly sized, a far cry from the enormous dinosaurs of the subsequent Jurassic and Cretaceous Periods.
Ingentia prima was big - up to 32 feet (10 meters) long - but not almost as large as the massive titanosaurs that lived millions of years after it. It was at least twice as large as the other plant-eaters that shared the warm, savannah environment it inhabited.
Gigantism proved a successful evolutionary survival strategy, especially for herbivorous animals, because size is a form of defense against predators.
"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", said Apaldetti. However, unlike the diplodocus and other later sauropod relatives, lessemsaurids stood on bent legs and had bones which grew in short, accelerated bursts.
Ingentia, known from two partial skeletons, was discovered in Argentina's San Juan Province.