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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Illuminating the Evolution of Animal Life – Humbling Thoughts

Recently two scientific papers have been published that delve deep into the origins of life on Earth.  In one paper, published in the “Proceedings of the National Academy of Sciences USA”,  the origins of animal body plans (Animalia) were explored, analysing the anatomical designs of animals, looking at how animal life half a billion years ago evolved and changed over time to bring us the biodiversity we see today and that which is preserved in the fossil record.

Tracing the Origins of the Animalia

This study mapped shared characteristics and one of the conclusions drawn from the research was that all those weird and wonderful Cambrian creatures, as preserved in the Burgess Shales of British Columbia or in the Sirius Passet Lagerstätte of Greenland, are actually less weird than the butterflies and birds that you might see in your own garden.

The Body Plans of Bizarre Cambrian Creatures Such as Hallucigenia are not that Bizarre According to a New Study

Picture credit: Royal Ontario Museum/Dr Jean Bernard Caron with additional annotation by Everything Dinosaur

In the second scientific paper, which shares a number of authors with the first publication and was published last month in the journal “Nature: Ecology & Evolution”, researchers examined the evolution of all life as a whole, conducting research using a new molecular clock analysis to plot a unified timescale for the early evolution of life on our planet.

What is the Molecular Clock?

The idea of a molecular clock is based on the idea that evolutionary changes occur at regular time intervals, that the rate of genetic change (mutation), has remained constant over time.  The molecular clock uses this premise, it plots the number of differences in the genomes of two living species (for example a human and a bacterium) and these changes are proportional to the time since they shared a common ancestor.

Using this methodology, the scientists, from the universities of Bath and Bristol were able to avoid putting too much reliance on a very fragmentary and often highly controversial early life fossil record. 

This research team concluded that the last universal common ancestor of cellular life existed more than 3.9 billion years ago and that the crown clades of two primary divisions of life – Eubacteria and Archaebacteria emerged less than 3.4 billion years ago.  Furthermore, the scientists concluded that modern eukaryotes (organisms whose cells have a nucleus enclosed within membranes – animals, protists, plants and fungi), don’t constitute a primary lineage of life and emerged relatively late during life on Earth’s evolutionary history (around <1.84 billion years ago).

Eukaryote Cell Compared to the Prokaryote Cell Typical of Eubacteria and Archaebacteria

Picture credit: Everything Dinosaur

Did Animal Body Plans Emerge Over Deep Time or Come About in Response to Sudden Changes?

This was the question that the researchers set out to answer in the paper published the “Proceedings of the National Academy of Sciences USA”.  It is agreed that complex animal life evolved from single celled eukaryotes and that multi-cellular animals diversified into thirty or forty distinct anatomical body plans, but when and how did these body plans emerge?  Were the majority of these different body plans already in existence after the Cambrian explosion, some 500 million years ago?

To answer these questions the research team, consisting of scientists from Bristol University, Dartmouth College in New Hampshire and the University of West Georgia, looked at features from living groups of animals and cross-referenced those characteristics against what can be identified from the fossil record.

Professor Philip Donoghue (Bristol University) a co-author of both scientific papers explained:

“This allowed us to create a ‘shape space’ for animal body plans, quantifying their similarities and differences.  Our results show that fundamental evolutionary change was not limited to an early burst of evolutionary experimentation.  Animal designs have continued to evolve to the present day, not gradually as Darwin predicted, but in fits and starts, episodically through their evolutionary history.”

Mapping the Evolution of Different Types of Animal Body Plan

Picture credit: Bristol University

The research team propose that major expansions in the type of animal following the Cambrian explosion aligns with other major ecological transitions such as the conquest of terrestrial environments.

Bradley Deline (University of West Georgia) added:

“Our results are important in that they highlight the patterns and pathways in which animal body plans evolved.  Many of the animals we are familiar with today are objectively bizarre compared with the Cambrian weird wonders.  Frankly, butterflies and birds are stranger than anything swimming in the ancient sea.”

Trying to Fit Extinct Animals into the Study

Contributors to both scientific papers, James Clark (Bristol University) and Mark Puttick (Milner Centre for Evolution, University of Bath), looked at how fossils could be incorporated into this research.

Dr Puttick stated:

“One of the problems we had is that our study is mostly based on living species and we needed to include fossils.  We solved the problem through a combination of analysing the fossils and using computer models of evolution.”

James Clark added:

“The fossils plot intermediate of their living relatives in shape space.  This means that the distinctiveness of living groups is a consequence of the extinction of their evolutionary intermediates. Therefore, animals appear different because of their history rather than unpreserved jumps in anatomy.”

Studying the Genomes of Different Animals (Animalia)

Jenny Greenwood, also from the University of Bristol’s School of Earth Sciences, wanted to explore how this study might be reflected in the genomes of different organisms.  She wanted to work out which of the many proposed genetic mechanisms drove the evolution of animal body plans.

Jenny commented:

“We did this by collecting data on the different genomes, proteins, and regulatory genes, that living animal groups possess.  The differences in anatomical designs correlate with regulatory gene sets, but not the type or diversity of proteins.  This indicates that it is the evolution of genetic regulation of embryology that precipitated the evolution of animal biodiversity.”

These researchers have concluded that animal evolution has been permitted or driven by gene regulatory evolution.

Two Papers Helping to Improve our Understanding of the Evolution of Life on Earth

Picture credit: Everything Dinosaur

Everything Dinosaur acknowledges the help of a press release from Bristol University in the compilation of this article.

The two scientific papers:

“Integrated Genomic and Fossil Evidence Illuminates Life’s Early Evolution and Eukaryote Origin” by Holly C. Betts, Mark N. Puttick, James W. Clark, Tom A. Williams, Philip C.J. Donoghue and Davide Pisani published in the journal Nature: Ecology & Evolution.

“Evolution of Metazoan Morphological Disparity” by B. Deline, J. Greenwood, J. Clark, M. Puttick, K. Peterson and P. Donoghue  published in the Proceedings of the National Academy of Sciences USA.

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Scientists find Kayentatherium wellesi Fossil Along with Young

The Order Mammalia has a number of distinguishing characteristics when compared to the other vertebrates.  For example, mammals tend to have bigger brains and tend to produce some of the smallest numbers of offspring per litter.  Mammals evolved from reptiles and at some point in their evolutionary history, larger brains developed and smaller broods became the norm.  Scientists writing in the academic journal “Nature”, have published details of the discovery of the fossilised remains of a Jurassic stem mammal, one that was found in association with thirty-eight babies.

The fossilised specimens might help palaeontologists to work out how mammals developed a different approach to reproduction when compared to their reptilian ancestors.

A Skeletal Reconstruction of the Probable Mother (Kayentatherium wellesi) and Offspring

Picture credit: Eva Hoffman/The University of Texas at Austin

Jurassic Stem Mammal Kayentatherium wellesi

The fossils represent Kayentatherium wellesi, a cynodont, it was only as the specimen was being prepared that the researchers realised that this was an exceptional fossil.  The find of a 185-million-year-old K. wellesi with offspring are the only known fossils of baby stem mammals with what is believed to the mother.

The presence of so many offspring, probably only recently hatched from their eggs when they died, indicates that these types of stem mammal had litters more than twice the size of any living member of the Mammalia.  The size of the brood is akin to the breeding strategy of extant reptiles

Lead author of the study, Eva Hoffman (who studied the fossils whilst a graduate student at the University of Texas at Austin), commented:

“These babies are from a really important point in the evolutionary tree.  They had a lot of features similar to modern mammals, features that are relevant in understanding mammalian evolution.”

The Kayenta Formation of Arizona

Hoffman co-authored the study with her graduate adviser, Jackson School Professor Timothy Rowe, who collected the specimen during fieldwork exploring the Early Jurassic sediments of the Kayenta Formation in Arizona, more than eighteen years ago.

Computerised tomography was used to reveal the bones inside the matrix back in 2011.  However, advances in CT-scanning finally permitted researchers at the University of Texas at Austin to reveal the babies, including complete skulls and partial postcranial material.

Advances in Computerised Technology Over the Last Seven Years Permitted the Fine Details of the Babies to be Discerned

Picture credit: Eva Hoffman/The University of Texas at Austin

The Skulls of the Babies – The Same as the Adult’s Only Smaller

The highly detailed computer-generated images permitted the researchers to verify that the tiny bones were Kayentatherium wellesi, the same as the adult.  The analysis revealed that the skulls were scaled-down replicas of the adult, only ten percent the size of an adult skull, but otherwise proportional.  This contrasts with extant mammals, as their babies are born with shortened faces and large skulls to accommodate a big brain.  The brain of mammals is a very energy demanding organ, for example, in humans the brain needs more energy than any other organ of the body.

It has been estimated that the brains of human beings require around 20% of the total energy needed by our bodies each day.  Breeding and producing offspring also requires a lot of energy.  The discovery that Kayentatherium, a stem mammal, had a tiny brain and many babies, despite otherwise having much in common with extant mammals, suggests that a critical step in the evolution of the Mammalia was trading large litters for large brains.  This evolutionary change is therefore likely to have taken place more recently than 185 million-years-ago.

Professor Rowe explained:

“Just a few million years later, in mammals, they unquestionably had big brains and they unquestionably had a small litter size.”

Where does the Jurassic Stem Mammal Kayentatherium Sit on the Mammalian Evolutionary Tree?

Kayentatherium was very probably endothermic (warm-blooded) and the skeleton shows a number of anatomical traits associated with modern mammals.

The Place of Kayentatherium on the Mammalian Family Tree

Picture credit: Eva Hoffman/The University of Texas at Austin

The mammalian approach to reproduction directly relates to our own species development (Homo sapiens), including the development of our own brains.  By looking back at our early mammalian ancestors, we can learn more about the evolutionary process that helped shaped the development of humans.

Professor Rowe added:

“There are additional deep stories on the evolution of development and the evolution of mammalian intelligence and behaviour and physiology that can be squeezed out of a remarkable fossil like this now that we have the technology to study it.”

The scientific paper: “Jurassic Stem Mammal Perinates and the Origin of Mammalian Reproduction and Growth” by Eva A. Hoffman and Timothy B. Rowe published in Nature.

Everything Dinosaur acknowledges the assistance of a press release from the University of Texas at Austin in the compilation of this article.

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