Bones reveal that brontosaurus had an older, more massive cousin in South Africa: NPR

Millions of years before Brontosaurus traveled the Earth, a massive parent crisscrossed South Africa.

Scientists believe that this ancient Jurassic dinosaur was the greatest terrestrial creature of all time. And unlike the larger creatures that arrived later, they think it might appear on their hind legs.

They nicknamed the newly discovered dinosaur Ledumahadi mafube, which translates into sesotho language "a giant thunderclap at dawn". And the discovery highlights how giants like Brontosaurus have become so huge.

The discovery did not happen quickly – it took years to get this dinosaur out of the ground. "It's a pretty long and fairly long story, I think it starts around 1990," says Blair McPhee, a paleontologist at the University of São Paulo, one of the researchers who discovered the dinosaur.

McPhee says some big bones have been discovered near the border of South Africa with Lesotho during a construction project. They were brought to the University of the Witwatersrand, where they sat for more than a decade.

Years later, a scientist came across other bones coming out of the rock in the same area. A team spent four or five years searching them thoroughly.

"It took a long time because the sediments in which they were locked up had been turned into concrete for about 200 million years and it was sort of on a slight cliff," McPhee said.

The tests showed that these bones matched those found in the 90s. And what was immediately clear was that this creature was huge. He would have weighed about 12 tons.

As McPhee said, they think he had "about twice the volume of an African elephant".

At about the same time the creature wandered, it was thought that the dinosaurs were smaller. "I was really surprised that they found a dinosaur as big, as old," says Michael D 'Emic, a professor of biology at Adelphi University, specializing in the field of medicine. evolution of dinosaur growth.

And there was something else surprising.

Researchers believe that this dinosaur evolved from a smaller ancestor who walked on two legs. And it's probably a precocious cousin of even larger animals like Brontosaurus, a type of herbivore called a sauropod that crawled on all fours.

McPhee says it's a transition dinosaur.

While digging the bones, they noticed that the front legs of the dinosaur were remarkably different from those of his later parents.

In fact, his front legs are more like those of smaller and smaller dinosaurs, who used these limbs to catch things. These animals "had a striking hand and they even had some sort of rudimentary thumb," says McPhee.

And its hind legs are like huge columns, like those of an elephant or a brontosaurus.

Scientists think that this dinosaur could have stood on two legs for, say, nibbling tall branches, but that he was walking mainly on all fours. This adaptation helped to stabilize the huge dinosaur – and that may have helped his close relatives grow even more.

And there were still those front legs.

McPhee says that he sees L. mafube like "the animal who wanted to have everything, who wanted to have everything".

To find out if the animal was walking on two or four legs, the team compiled a database containing measurements and proportions of live animals and used it to infer how L. mafube probably market. "Generally, if something had proportions of members of this particular type, it correctly predicted the type of locomotion it would represent," McPhee said.

He says that "the idea that it would be predominantly bipedal seems improbable because of its size".

The researchers published their findings Thursday in the journal Current Biology.

It's a robust period to be a paleontologist. Dr. Emic says that dozens of dinosaurs have already been discovered this year – and that new discoveries can potentially change the common wisdom of the relationship between dinosaurs.

"There is a lot of reshuffling of our understanding and improvement of our understanding," said Emic. "This is not the end of the relationship between this animal and other animals, and I'm sure it will also spark a lot of research."