Newly named dinosaur species named largest land animal of its time

Sept. 27 (UPI) -- Paleontologists have discovered a new giant dinosaur species in South Africa's Free State Province. The plant-eating dinosaur weighed 12 metric tons and stood more than 13 feet tall at the hip, roughly twice the size of an African elephant.

Scientists named the species Ledumahadi mafube, Sesotho for "a giant thunderclap at dawn." The Sesotho language is indigenous to the region where the species was discovered.

"The name reflects the great size of the animal as well as the fact that its lineage appeared at the origins of sauropod dinosaurs," Jonah Choiniere, a professor of paleontology at South Africa's University of the Witwatersrand, said in a news release. "It honors both the recent and ancient heritage of southern Africa."

The proportions of the newly named species resemble a stouter version of the dinosaur's closest relatives, sauropods. Scientists believe Ledumahadi mafube evolved its tremendous size independent of sauropods.

"The first thing that struck me about this animal is the incredible robustness of the limb bones," said researcher Blair McPhee.

The slight anatomical differences between the species and its sauropod relatives -- thicker hind legs and crouched forelimbs -- suggest Ledumahadi mafube was a kind of evolutionary experiments in body shape.

According to the paper detailing Ledumahadi mafube, published Thursday in the journal Current Biology, the species' somewhat awkward experiment in size and locomotion is a reminder that evolution rarely happens smoothly.

That the slender but still massive sauropods came to dominate the Late Jurassic, yielding species weighing as much as 60 metric tons, suggests their approach to gigantism was more efficient and effective. Their evolutionary success, however, occurred alongside related experiments and failures.

"The path towards gigantism in sauropodomorphs was far from straightforward," McPhee said.

Ledumahadi mafube offers a snapshot of the transitional path -- from small and bipedal to big and quadrupedal.

Scientists were able to characterize Ledumahadi mafube's anatomical uniqueness using a novel bone tissue analysis method.

"We can tell by looking at the fossilized bone microstructure that the animal grew rapidly to adulthood," said Jennifer Botha-Brink from the South African National Museum in Bloemfontein. "Closely-spaced, annually deposited growth rings at the periphery show that the growth rate had decreased substantially by the time it died."