The Largest Dinosaur Fossil Excavated for the First Time in South Africa
Scientists have excavated the largest dinosaur fossil which would have been the largest terrestrial animal on our planet.
A team of scientists from South Africa, UK and Brazil led by University of Witwatersrand have discovered a fossil of a new species of dinosaur in South Africa thought to be a related to brontosaurus. This early Jurassic dinosaur weighed a huge 26,000 pounds i.e. double the size of an African elephant, and stands four meters at hip. It has been named ‘Ledumahadi mafube’ meaning ‘giant thunderclap at dawn’ in the indigenous language Sesotho of the region where it was discovered.
A gigantic dinosaur
This animal is found to be unique not just in its gigantic size but also its evolutionary history. The chance discovery was first initiated upon discovering a partial skeleton of an unknown dinosaur literally sticking out of rocks back in 2012 during a field visit. Once researchers realised how huge the size of the thigh bone was, it dawned on them about the humungous size of this animal. After years of excavation, fossil of an adult dinosaur was uncovered thought to be at least 14 years old and weighing 12 tons at time of death. Fossil’s bone tissue analysis using osteohistological examination helped establish age of the animal. The fossil bone microstructure reveals that this animal grew fast to adulthood and closely-spaced growth rings at the periphery show that growth rate had decreased substantially confirming that it had reached adulthood.
An evolutionary transition
Ledumahadi is closely related to sauropod dinosaurs including the well-known species Brontosaurus and Diplodocus. It was a plant-eating herbivore, had thick limbs and was a quadruped i.e. it walked on all four legs in a posture similar to modern elephants. Compared to sauropod’s long, slender columnar limbs, Ledumahadi’s forelimbs were more crouched i.e. it had more flexed limbs like primitive dinosaurs. Their ancestors walked on two legs only and they must have adapted to walk on all four and that is why they grew larger to support digestion as they were herbivores.
Researchers compared fossil data from dinosaurs, reptiles etc who walked on two or four legs and they measured limb size and thickness. This is how they concluded Ledumahadi’s posture and its way of walking on all four limbs. It is understood that many other dinosaurs must have experimented walking on all four limbs which could optimally balance a bigger body. Based upon these collective observations, researchers say that Ledumahadi was definitely a ‘transitional’ dinosaur, as it had ‘crouched’ yet very thick limbs to support its large body. Their limb bones– both arms and legs - are very robust and similar in shape to giant sauropod dinosaurs but obviously thicker while sauropods had more slender limbs. The evolution of four-legged postures came before their giant bodies. Just sheer size and elephant-like limb posture helped them, example sauropods, to become one of the most dominant dinosaur groups during the Jurassic era. Ledumahadi definitely represents a transitional stage between two major groups of dinosaurs. The group of early dinosaurs were experimenting with various ways of becoming bigger in size during the first tens of millions of years of their evolution. What it means for research is that the evolutionary transition from a small, bipedal creature to a large, quadrupled sauropod is a complex path and this evolution certainly led to survival and achieving dominance.
The discovery published in Current Biology tells us that even more than 200 million years ago, these dinosaurs were the largest vertebrates to be present on the planet, and this time period was almost 40-50 million years earlier than giant sauropods were first seen. The new dinosaur is closely related to giant dinosaurs who lived in Argentina around that time supporting the idea that all continents that we see today were assembled as Pangea – a supercontinent comprised of world’s land mass during Early Jurassic. And at that time this region of South Africa was not mountainous as we see it today but was flat and semi-arid with shallow streams. Certainly, it was a thriving ecosystem. Like Ledumahadi, many other dinosaurs - both giant and tiny - roamed the place at the time. It is fascinating that South Africa has helped to understand the rise of giant dinosaurs during Jurassic era.
This is another remarkable discovery to be made in South Africa, a region making Palaeontology breakthroughs due to its significant geography. Though complete skeleton of this gigantic dinosaur is not available yet, and other species are still to be discovered but if Ledumahadi was around today, it would have been the largest terrestrial animal on our planet.
Blair W. McPhee et al., 2018, ‘Giant Dinosaur from the Earliest Jurassic of South Africa and the Transition to Quadrupedality in Early Sauropodomorphs, Science, vol. 28, no.19,