Bones reveal that brontosaurus had an older, more important cousin in South Africa

Updated at 20:57 ET

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

Scientists believe that this ancient Jurassic dinosaur was, at the time, 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 the Mesotho language "a giant thunderclap at dawn". And the discovery sheds light on how giants like Brontosaurus have become so huge.

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

McPhee says some huge bones were found near the South African border 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 lot of time because the sediments in which they were encased actually were turned into concrete about 200 million years ago, and it was sort of on a small cliff, "says McPhee.

Tests have shown 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 that was so big and old," said Michael D'Emic, assistant professor of biology at Adelphi University, a specialist in the evolution of dinosaur growth. did not participate in the research.

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 the researchers searched the bones, they noticed that the front legs of the dinosaur were remarkably different from those of their close relatives.

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

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

Scientists believe that this dinosaur could have stood on two legs to, for example, nibble high branches, but that he walked mainly on all four legs. 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 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 that kind of proportion in the limbs, it would predict correctly what type of locomotor it would be," says McPhee.

He says: "The idea that it would be mainly biped seems unlikely because of its size."

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

It's a robust period to be a paleontologist. According to D'Emic, several dozen dinosaurs have already been discovered this year. New discoveries could potentially change the common wisdom of how dinosaurs relate to each other.

"There is a lot of redistribution of our understanding and understanding," says D'Emic. "This is not the end in itself of how this animal is related to other animals, and I'm sure it will also stimulate a lot more research."

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