This is an artist's reconstruction of Ledumahadi mafube foraging in the Early Jurassic of South Africa. In the foreground, Heterodontosaurus (another South African dinosaur). CREDIT: Viktor Radermacher/University of the Witwatersrand
'Giant thunderclap' dinosaur discovered
01:10 - Source: CNN

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A newly discovered dinosaur species was the largest land animal of its time

The dinosaur is considered an evolutionary experiment due to its giant size and posture

CNN  — 

If humans had lived 200 million years ago, they would have marveled at the largest dinosaur of its time. It’s name means “a giant thunderclap at dawn.”

The recently discovered fossil of a new dinosaur species in South Africa revealed a relative of the brontosaurus that weighed 26,000 pounds, about double the size of a large African elephant.

The researchers have named it Ledumahadi mafube, which is Sesotho for “a giant thunderclap at dawn.” Sesotho is an official South African language indigenous to the part of the country where the dinosaur was found.

“The name reflects the great size of the animal as well as the fact that its lineage appeared at the origins of sauropod dinosaurs,” said Jonah Choiniere, study author and paleontology professor at the University of the Witwatersrand in Johannesburg, South Africa. “It honors both the recent and ancient heritage of southern Africa.”

Apart from its massive size, there are other evolutionary details about the new species that make it entirely unique, according to a new study published Thursday in the journal Current Biology.

“It shows us that even as far back as 200 million years ago, these animals had already become the largest vertebrates to ever walk the Earth,” Choiniere said.

Finding a new dinosaur

Choiniere’s graduate student, Blair McPhee, discovered the bones of an unknown dinosaur in 2012.

“Blair told me how important he thought it was, and even showed me that some of its bones were still sticking out of the rocks in the field,” Choiniere said.

Over years of excavation, the team uncovered the fossil of a fully-grown adult dinosaur, likely about 14 years old when it died.

Ledumahadi was a close relative of sauropod dinosaurs, like the brontosaurus and others that ate plants and walked on all four legs. But the fossil shows that it evolved earlier, and independently, of sauropods.

This figure shows some of the preserved elements of the newly discovered dinosaur.

Sauropods had a posture and thick, column-like limbs that are very similar to elephants. But they evolved from ancestors that walked predominantly on two legs. Adapting to walk on all fours allowed sauropods to grow larger and supported the digestive process needed for their herbivore diet.

The researchers believe that Ledumahadi was a transitional dinosaur, an evolutionary experiment itself during the Early Jurassic period. The forelimbs of this dinosaur are more “crouched,” while being very thick to support its giant body.

“The first thing that struck me about this animal is the incredible robustness of the limb bones,” said McPhee, lead study author. “It was of similar size to the gigantic sauropod dinosaurs, but whereas the arms and legs of those animals are typically quite slender, Ledumahadi’s are incredibly thick.”

The researchers wanted to find out whether or not this dinosaur walked on two or four legs, so they developed a new method to test it. They compiled data of dinosaurs, animals and reptiles that walked on two or four legs, including leg measurements and thickness. Comparing the data from the fossil with this dataset enabled them to determine Ledumahadi’s posture.

While the method helped them determine that Ledumahadi walked on four legs, it also revealed that other early similar dinosaurs were also experimenting with walking on all fours.

“The evolution of sauropods isn’t quite as straightforward as we once thought,” Choiniere said. “It appears that sauropodomorphs evolved four-legged postures at least twice before they gained the ability to walk with upright limbs, which undoubtedly helped make them so successful in an evolutionary sense.”

Location is key

The newly discovered dinosaur is a close relative of gigantic dinosaurs that lived during the same time in Argentina, which supports the idea that all of the continents were still assembled as Pangea, a supercontinent made up of most of the world’s land mass during the Early Jurassic.

“It shows how easily dinosaurs could have walked from Johannesburg to Buenos Aires at that time,” Choiniere said.