Ledumahadi mafube – Giant Plant-eater from the Early Jurassic

A new species of giant sauropodiform from the Early Jurassic of South Africa has been named and described. The dinosaur has been named Ledumahadi mafube and is estimated to have weighed around twelve tonnes and stood about four metres high at the hips. L. mafube may have been the largest animal alive on Earth between 200 and 195 million years ago.

Over the course of the Jurassic, gigantic sauropod genera evolved, famous giants such as Brontosaurus, Brachiosaurus and Diplodocus.  Writing in the journal “Current Biology”, the international research team led by Professor Jonah Choiniere (Witwatersrand University), concluded that Ledumahadi shows that quadrupedal sauropodomorphs which lacked the columnar limbs of the later sauropods could still attain, massive sauropod-like body sizes.  This challenges one of the assumptions held in palaeontology, that the evolution of column-like legs was a prerequisite that enabled the long-necked, lizard-hipped dinosaurs to grow so big.

A Life Reconstruction of the Newly Described Sauropodiform Ledumahadi mafube

Picture credit: Viktor Radermacher (Witwatersrand University)

The illustration shows the twelve tonne South African giant Ledumahadi mafube with its bent, semi-erect forelimbs.  It is observed by a much smaller Early Jurassic dinosaur, the ornithischian Heterodontosaurus tucki.

“Giant Thunderclap at Dawn”

The fossil material consists of disarticulated post-cranial material discovered at Beginsel farm, approximately fifteen miles southeast of the town of Clarens in Free State Province, close to the border of South Africa and Lesotho.  The fossils were found in mudstone from the upper Elliot Formation representing terrestrial sediments laid down between 200 and 195 million years ago (Hettangian to Sinemurian faunal stages of the Early Jurassic).

The Fossilised Remains of Ledumahadi mafube and Location Maps

Picture credit: Witwatersrand University

The dinosaur’s name, pronounced Le-dew-ma-har-dee maf-fu-be is from the local Sesotho dialect of the region.  It translates as “giant thunderclap at dawn”, reflecting the size of the animal and the stratigraphically early position of this taxon.

The Origins of Sauropod Dinosaurs

Commenting on the significance of the name, Professor Choiniere stated:

“The name reflects the great size of the animal as well as the fact that its lineage appeared at the origins of sauropod dinosaurs.   It honours both the recent and ancient heritage of southern Africa.”

Fossil Bones Photographed at the Quarry Site

Picture credit: Witwatersrand University

An Adult Dinosaur Around Fourteen Years Old When it Died

An analysis of the growth lines of the limb bones indicate that the specimen was fully grown when it died and that this dinosaur was approximately fourteen years old when it met its demise.  The research team compared the limb measurements of the front and hind limbs of Ledumahadi with other dinosaurs and extant tetrapods and they concluded that this dinosaur, had very robust limbs and was a quadruped, which weighed around twelve tonnes.  The plant-eating Ledumahadi was a giant amongst the Early Jurassic Dinosauria, it is the largest animal known so far from Early Jurassic sediments more than 195 million years old.  When Ledumahadi roamed it may have been the largest animal on Earth at the time.

Professor Choiniere and the Distal Portion of the Right Femur of Ledumahadi

Picture credit: Witwatersrand University

A Different Stance and Posture Compared to Later Sauropods

The scientists, which included Roger Benson from Oxford University, conclude that L. mafube had a different posture than later sauropods.  It did not have the column-like limbs of dinosaurs like Brontosaurus, Brachiosaurus and Diplodocus, its forelimbs would have been more crouched and partially flexed.  The research team postulate that this posture was an evolutionary experiment with gigantism within the lizard-hipped reptiles.

Lead author of the paper, Dr Blair McPhee (Witwatersrand University), explained:

“The first thing that struck me about this animal is the incredible robustness of the limb bones.  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.”

Professor Choiniere Compares A Giant Toe Claw Bone (Pedal Ungual) with His Hand

Picture credit: Witwatersrand University

A Transitional Form of Long-necked Dinosaur (Ledumahadi mafube)

Analysis of the bones and comparative studies with other sauropods and extant tetrapods, led the scientists to conclude that the internal structure of the bones of Ledumahadi displayed traits associated with basal sauropodomorphs and more derived members of this group.  L. mafube probably represents a transitional stage between the sauropodomorphs and the later true Sauropoda.

Limb Bone Study Has Helped Plot the Evolutionary Change from Bipedalism to a Quadrupedal Stance

Picture credit: Witwatersrand University

The picture above depicts silhouettes scaled in height to the cube root of mass estimate of the taxon.  The colour of the silhouettes represents the inferred posture; red is bipedal, and black equals quadrupedal.   The purple line marks the Triassic/Jurassic boundary.

Out-competed by the Columnar-limbed Sauropods

Ledumahadi may have been the biggest animal on Earth during the very Early Jurassic, but the fossil record indicates that this large dinosaur body-plan with flexed limbs and a more crouched posture was not to last.

Co-existing with Ledumahadi were primitive sauropods such as Vulcanodon (V. karibaensis), which although smaller had column-like limbs.  Within a few million years, only the columnar-limbed sauropods remained as the only surviving lineage.  The reasons for this faunal turnover are unclear, but it might reflect that Ledumahadi might have had to expend more energy moving about with its flexed limbs that were not held directly under the body.  The more energy efficient posture of the straight-legged sauropods with their column-like legs may have provided a competitive edge, driving dinosaurs like Ledumahadi to extinction.

To read Everything Dinosaur’s article about a recently described long-necked, Early Jurassic sauropodiform from China that is also helping palaeontologists to better understand sauropod evolution:  Yizhousaurus Helping to Give Sauropod Evolution a Head Start.

The scientific paper: “A Giant Dinosaur from the Earliest Jurassic of South Africa and the Transition to Quadrupedality in Early Sauropodomorphs” by Blair W. McPhee, Roger B.J. Benson, Jennifer Botha-Brink, Emese M. Bordy & Jonah N. Choiniere published in the journal “Current Biology”.

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Jinguofortis perplexus – A Mosaic of Dinosaur and Bird Features

Scientists from the Chinese Academy of Scientists have described a new species of ancient, Early Cretaceous bird with a mosaic of dinosaur and bird characteristics.  The bird, which has been named Jinguofortis perplexus, lived approximately 127 million years ago and it will help palaeontologists to learn more about bird development and the evolution of powered flight in the avian dinosaurs.

Jinguofortis perplexus

An Illustration of the Newly Described Early Cretaceous Bird Jinguofortis perplexus

Picture credit: PNAS (Chung-Tat Cheung)

The pigeon-sized bird does not have a long bony tail, a characteristic inherited from dinosaurs that is found in the first birds such as Archaeopteryx.  Instead, the tail is much reduced and ends with a compound bone, a pygostyle, possessed by modern birds today.  Jinguofortis perplexus represents a transitional form, after birds had lost their dinosaurian tails but before they had evolved a fan of flight feathers on their shortened, compressed tails.

Honouring the Contribution of Female Scientists

The fossil specimen comes from the Debeigou Formation of north-eastern China and the genus name “Jinguofortis” derives from the Mandarin word for female warrior “jinguo” and the Latin word “fortis” meaning brave and strong.  The name honours the contribution made to palaeontology by female scientists around the world.  The species or trivial name “perplexus” is from the Latin and reflects the puzzling mix of anatomical traits.  Jinguofortis has been assigned to a basal member of the clade of short-tailed birds (Pygostylia).

The Slab and Counter Slab of the Fossil Bird Jinguofortis perplexus

Picture credit: PNAS (Proceedings of the National Academy of Science)

Avian and Dinosaurian Characteristics

Writing in the academic journal “Proceedings of the National Academy of Sciences (USA)”, the researchers Wang Min, Thomas Stidham and Zhou Zhonghe (Chinese Academy of Sciences), describe a unique combination of anatomical traits, including a jaw with small teeth like Jinguofortis’s theropod dinosaur relatives as well as a short bony tail ending in a pygostyle.  Gizzard stones associated with the well-preserved, but rather flattened fossil, indicate that Jinguofortis may have fed on seeds and other plant material.  Jinguofortis also possessed a third finger with only two bones, unlike other early birds.

For dinosaur and prehistoric animal models: Prehistoric Animal Models.

Fused Shoulder Bones

Close examination of the slab and counter slab revealed that the shoulder girdle of Jinguofortis was fused into a single bone, the scapulocoracoid, a feature associated with the non-avian dinosaurs.  Modern birds usually have two bones the scapula and the coracoid that provide greater flexibility in the shoulder, ideal for flapping, powered flight.  The fossil’s shoulder joint also gives clues about its flight capacity.  In flying (volant) birds, the shoulder, which experiences high stress during flight, is a tight joint between the two unfused bones (scapula and the coracoid).  In contrast, Jinguofortis perplexus with its fused bones suggests that it flew in a different way compared to modern birds.

Changes in the Coracoid and Scapula (Shoulder Girdle) in Vertebrates

Picture credit: Wang Min (Chinese Academy of Sciences)

The picture above plots the main changes in the shoulder joint of vertebrates from fish through to tetrapods such as amphibians, reptiles and mammals.  The second part of the diagram maps the evolution of the shoulder joint from the Dromaeosauridae (the raptors), through to avian dinosaurs (birds) and shows that Jinguofortis sits between the earlier Confuciusornithiformes and the later Sapeornithiformes and is basal to the Pygostylia.  The diagram provides a temporal reference and also illustrates the evolution of the bird hand with its much reduced digits from dinosaurian ancestors with their grasping hands.

Measuring the Fossil Wing of Jinguofortis perplexus

Measurement of the fossil’s wing size and estimation of its body mass show that the extinct species had a wing shape and wing loading (wing area divided by body mass) similar to living birds that need a lot of manoeuvrability.  Jinguofortis lived in a dense forest.  Its body plan would have assisted it to dodge and weave through the branches and dense foliage as it flew.

Jinguofortis perplexus with its mosaic of bird and dinosaur characteristics suggests that the evolution of modern birds was more complex than previously thought.

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