Approximately twice the size of a modern-day African elephant, Ledumahadi mafube was the world's largest land animal when it existed almost 200 million years ago. Despite this fact, none of the dinosaur's fossilized remains were discovered until relatively recently, and it has only now been scientifically classified.

After some of the animal's bones were initially discovered about 30 years ago, more were subsequently unearthed in South Africa's Free State Province, in 2012. Based on the growth rings in the fossils, the individual they belonged to is believed to have been an adult approximately 14 years old.

The plant-eating creature's newly-coined name means "a giant thunderclap at dawn" in the region's native Sesotho language. This refers to its estimated weight of 12 tonnes (13 US tons) and height of 4 meters (13 ft) at the hips, along with the fact that it lived at the "dawn" of the reign of the sauropod dinosaurs, of which it was an early close relative. Sauropods included everyone's favorite dinosaur, the Brontosaurus.

By analyzing measurements of its front and rear limb bones, an international team of scientists has determined that Ledumahadi mafube walked on all fours, although it didn't go about doing so in the same fashion as the sauropods. Whereas they had legs that extended straight down from their bodies (like elephants do), Ledumahadi's front legs were more crouched, protruding out to either side. This suggests that it represents an early experiment in giant body size, having itself evolved from bipedal ancestors.

"The first thing that struck me about this animal is the incredible robustness of the limb bones," says lead author of the study, Dr. Blair McPhee of Johannesburg's University of the Witwatersrand. "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. To me this indicated that the path towards gigantism in sauropodomorphs was far from straightforward, and that the way that these animals solved the usual problems of life, such as eating and moving, was much more dynamic within the group than previously thought."

A paper on the research, which led by U Witwatersrand palaeontologist Prof. Jonah Choiniere, was published this week in the journal Current Biology.

Editor's note: This article originally contained an error regarding how long ago Ledumahadi mafube lived. The correct figure is almost 200 million years ago.

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