Dreadnoughtus schrani, one of the largest land animals of all time, had a two-story height on the roadside. Its tail was almost as long as an urban bus, and it tipped the scales at around 65 tons, heavier than a fully loaded semi-truck.
Other enormous dinosaurs are known based on a few bone fragments found, but the recently discovered remains of Dreadnoughtus are so complete and beautifully preserved that they will provide an unprecedented insight into how the largest dinosaurs were related to each other, how fast they grew, and how something so heavy moved around. In fact, never before have so many representative pieces of such a large dinosaur been found.
“It’s a really important discovery,” says paleontologist Michael D’Emic of Stony Brook University, who is not associated with the new finding, reported in this week’s edition of the journal Scientific Reports. “The glimpses we have of those small, big dinosaurs are quite fleeting. (Dreadnoughtus) will serve as a key to understanding all those other more fragmented specimens.”
The integrity of the Dreadnoughtus remains, discovered in Argentina in 2005 and examined between 2005 and 2009, allowed scientists to accurately estimate its weight.
At 65 tons, Dreadnoughtus was heavier than many models of the Boeing 737. It is the largest dinosaur whose weight can be accurately calculated, says discoverer Kenneth Lacovara of Drexel University, who named the huge 20th-century battleships called dreadnoughts after it.
However, Lacovara admits that there is a “good possibility” that a dinosaur known as Argentinosaurus was heavier than Dreadnoughtus.
Paleontologist Roger Benson of the University of Oxford, who was not affiliated with the new finding, also places Dreadnoughtus behind Argentinosaurus, which may have weighed up to 90 tons.
Although it was an herbivore, it was equipped for combat with a muscular tail that could have been used as a weapon and large claws on its hind legs. Its size would have made it the king of the forests where it lived in the late Cretaceous period.
“If this thing just leaned on a T. Rex, it would probably kill it,” says Lacovara. Walking towards it “would be like approaching a living building… It would be quite overwhelming and not advisable.”
Although it could laugh at all onlookers, even Dreadnoughtus was not immune to the current of a swollen river.
About 80 million years ago, a large torrent swept away two Dreadnoughtuses, perhaps already dead, before throwing them onto a bed of sediment similar to quicksand. In a stroke of luck for scientists, the mud revealed the complete animals.
Thanks to the burial of the dinosaurs, Lacovara and his team recovered around 70% of the bones that Dreadnoughtus had below its head, the researchers report in Scientific Reports.
Until now, no more than 27% of the types of bones from any large dinosaur had been found. Argentinosaurus, for example, is known from half a dozen vertebrae, a leg bone, and some remnants of hip bone, says Lacovara.
The new finding will serve as a Rosetta stone to unlock the mysteries of other enormous dinosaurs, says D’Emic.
For example, did these animals need to survive for a century to become so large, or would accelerated growth over a few decades be sufficient? (The fossil analysis suggests that it was still not fully grown).
This is a truly large animal,” says Lacovara. “It somehow amazes the imagination.
It stood two stories tall at the shoulder. Its tail was almost as long as an urban bus. And it tipped the scales at around 65 tons, heavier than a fully loaded semi-truck. Meet Dreadnoughtus schrani, one of the largest land animals of all time. Other enormous dinosaurs are known due to some…