The restricted size of the Patagonian site—about 4,300 square feet (400 square meters)—includes mollusks, leaves, fish, crocodile-like reptiles called crocodylomorphs, and other dinosaurs such as a flying pterosaur and a megaraptor whose claws reached 16 inches (40 centimeters).
Thanks to the unusually high number of the dino's intact bones having been found together, scientists can more accurately calculate not only the size of Futalognkosaurus but that of its rivals as well.
"The next step is to re-estimate the sizes of other large dinosaurs," Kellner said.
As the digging continues, Kellner expects more of Futalognkosaurus, potentially revealing that the giant dinosaur is even bigger than is believed.
"This is possibly the largest animal to walk on land," said Jeff Wilson, a paleontologist at the University of Michigan who reviewed the study.
The giant dinosaur may have been able to carry its weight because of its birdlike bones, he pointed out.
"You think the long neck must be heavy, but it isn't because of the hollow, air-filled bones," said Wilson.
"This makes them very difficult to collect, because they're so delicate."
Researchers hypothesize that the huge animal fell into a river basin, which helped preserve it and the other fossils. The dinosaur's carcass might have acted as a barrier against river water, collecting organic materials and allowing the material to be covered in sediment.
"That's why the animals fossilized," Kellner, of Brazil's National Museum, said.
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