Megalosaurus: The Original Dinosaur

An Artist reconstruction of Buckland’s great lizard
Image Credit: LadyofHats Mariana Ruiz,

There is no group of extinct life that enthrals the minds of the general public quite like dinosaurs. All palaeontologists both current and aspiring can claim to have at least been partially inspired by reading books and watching documentaries about dinosaurs, and from seeing their fossils and reconstructions in the many museums throughout the globe. Some dinosaurs have received vast amounts of media attention; the great Tyrannosaurus Rex; the three-horned Triceratops; and the long necked Brachiosaurus to name a few. However there is one dinosaur that can claim to be perhaps the most important of them all. Megalosaurus bucklandii is not as well-known as these other dinosaurs, which is quite surprising to me. However this medium-large sized theropod from the mid-Jurassic has every claim to live long in the history books.

Megalosaurus was the first dinosaur to be properly and scientifically described and the first animal to be referred to as a “dinosaur”. The first Megalosaurus fossils were discovered in the village of Stonesfield in Oxfordshire, England in the 18th century. These fossils came from a Mid-Jurassic (170-150 Million years old) deposit known as the “Stonesfield Slate”, a deposit that has also preserved the remains of other dinosaurs, pterosaurs, insects and plants of the time. The Megalosaurus fossils, originally described under the interesting name of Scrotum humanum, which was not formerly accepted by any scientific body, were passed on in 1824 to the geologist William Buckland, who in collaboration with the anatomist Georges Cuvier, identified the animal as a large extinct reptile. This animal was given the name Megalosaurus bucklandii, meaning “Buckland’s great lizard”. It was almost 20 years later in 1842 that Megalosaurus was referred to by Sir Richard Owen as a “dinosaur”. This discovery was quite unlike any living animal and captured the imagination of the Victorian public, with Megalosaurus making an appearance in the Charles Dickens novel Bleak House. This made it one of the first (but certainly not the last!) dinosaurs to appear in mainstream popular media.

A fossilised lower jaw and tooth of Megalosaurus. This jaw is one of the more iconic dinosaur fossils.
Image Credit: Wikimedia Commons,,_Megalosaurus_jaw.jpg

Most of the Megalosaurus specimens that these early Victorian geologists had to go on were incomplete, with the only finds being a lower jaw, upper jaw, some teeth and a few thigh and leg bones. In addition this was really the first time anyone had attempted to reconstruct dinosaurs from their bones. So the Victorian scientists could only make educated guesses as to what this animal was like. While they knew, based on its tooth anatomy, that it was related to reptiles the first reconstructions of Megalosaurus were very different to what we believe today. Basing its design on modern lizards Megalosaurus was reconstructed as a massive, sluggish four legged animal, with its tail dragging along the ground and possessing a big hump on its shoulders. This interpretation can be seen in all its glory at the Crystal Palace Park in London. Unveiled in 1851 it is displayed stalking a group of equally lizard like Iguanodon, also inaccurate as Iguanodon would appear almost 40 million years after Megalosaurus (to name one inaccuracy!). It was only when further theropod remains were found a few decades later that a more accurate picture of Megalosaurus became clear. However during this time the Megalosaurus species was known as a “wastebasket taxon” where any newly discovered large theropod remains were all haphazardly lumped into the Megalosaur group, like somebody chucking different types of cutlery into the same drawer. Also the animal was portrayed, like other bipedal dinosaurs at the time, standing upright like a Kangaroo. This would only change nearly a whole century later, where research in the 1960s and 1970s led to all bipedal dinosaurs’ posture being altered to the more horizontally balanced forms seen today, where the head and body were counterbalanced by a long, lofted tail.

The Megalosaurus model at Crystal Palace park. This model, first revealed in 1851, shows us what Victorian Scientists thought it looked like.
Image Credit: Chris Sampson,

Whilst Megalosaurus has a long and important story about its discovery, and how it changed scientific thinking forever, what was this dinosaur actually like when it was alive? Well, Megalosaurus belonged to a group of theropods known as the Megalosauridae. This group were the main land predators of the early to mid-Jurassic period, dominating the landscape until their numbers declined during the late Jurassic 150 million years ago. Megalosaurus had many of the features that are typical of theropod dinosaurs; big hind legs, saurischian (lizard-like) hips, arms ending in non-pronated wrists, sharp claws and robust jaws filled with razor sharp teeth suitable for cutting and biting into the flesh of its prey. The powerful legs of Megalosaurus would have enabled it to reach speeds of up to 20 miles per hour, equivalent to a modern day Grizzly Bear and easily fast enough to chase down its prey. Once caught Megalosaurus would have attacked its prey with a powerful bite, its skull built for heavy impact by having a framework of slightly loose bones that, through flexing on impact were able to absorb the forces involved in biting and holding large struggling prey. Reaching up to nine metres long, three metres tall and weighing nearly one and a half tonnes it was the undisputed top predator of mid-Jurassic England, hunting large herbivorous dinosaurs, such as the long necked sauropod Cetiosaurus. However it would have needed to be an unfussy eater. During the Mid Jurassic, the UK was broken up into small islands, with Megalosaurus probably swimming from island to island and combing the beaches for any food it could find, including any marine reptiles, crabs and pterosaurs that had been beached. It is also possible, like a lot of other theropods, that Megalosaurus could have been at least partially feathered. Evidence for this comes from another megalosaurid called Sciurumimus. Found in the Late Jurassic of Germany this juvenile megalosaur was found preserved with a filamentous coating of feathers. While this isn’t direct evidence of feathers on Megalosaurus the fact that it is present on a close relative means that it is likely that it too possessed a similar coating, making it look a bit less like a scaly lizard and a bit more like a fluffy carnivorous bird. This new finding, put forward in a 2014 study by Rauhut et. al., would certainly have startled William Buckland, Richard Owen and the other Victorian scientists that first named this remarkable beast a “dinosaur”.

So, just as the 2008 film “Iron Man” was the start of the Marvel Cinematic Universe, and the Benz Patent Motor Car was the origin of today’s cars, the discovery of Megalosaurus was the genesis of dinosaur research. While T-Rex and others get the spotlight nowadays without this first description and reconstruction of this Mid-Jurassic Megalosaur from Oxford, dinosaurs would not have captured the public imagination in quite the way that they have. The field of palaeontology would perhaps have never evolved into the science it is today, and who knows, in that world I may have become an archaeologist!

References/Further Reading

Rauhut et al 2014 paper about feather filaments in the Megalosaur Sciurumimus

Rauhut, O. W. M., et al. (2012). “Exceptionally preserved juvenile megalosauroid theropod dinosaur with filamentous integument from the Late Jurassic of Germany.” Proceedings of the National Academy of Sciences 109(29): 11746-11751.

The Friends of Crystal Palace Dinosaurs page on the Megalosaurus model at Crystal Palace park, including comparisons with how the Victorian scientists thought it looked and behaved compared with modern interpretations

“Megalosaurus”, Friends of Crystal Palace Dinosaurs,

More Information on Megalosaurus and other animals of the Stonesfield slate from the Oxford University Museum of Natural History website

“The Oxfordshire Dinosaurs”, Oxford University Museum of Natural History,

The Legend of the Sea Serpent Mosasaurus

Mosasaurus as it may have looked when it swam in Earth’s seas 70-65 million years ago.
Image Credit: Dmitry Bogdanov,

The idea of a large, serpentine like animal living in the depths of the ocean and battling heroes of legend has been a favourite tale of a whole host of myths and legends. Since early human history people seem to have been attracted to the idea of such an animal, quite unlike anything that lives today. Even in recent times this is a concept that has people enthralled. Just ask anybody who is convinced that there is a plesiosaur like animal living in Loch Ness. However while a large sea serpent probably doesn’t exist today (not counting real life sea snakes) there was a similar beast that ruled the seas of the Late Cretaceous period 70 million years ago. Its full scientific name, is Mosasaurus hoffmanni (Meaning “Hoffmanns Meuse Lizard”).

Mosasaurus was discovered back in 1764 near the town of Maastricht in the Netherlands. This was a time when the word “dinosaur” hadn’t been spoken yet, and proper scientific research on fossils was in its infancy. The fossil itself was a disarticulated skull, a cast of which is on display in the Sedgwick Museum in Cambridge. This fossil went through an eventful journey before it was first scientifically examined in the early 19th century, which includes being hidden from French occupation and being traded (allegedly) for 600 bottles of wine! Scientists of the time, including the famous French naturalist Georges Cuvier, correctly deduced that this animal was a reptile. Now “Meuse Lizard” may seems like a weird name to give an animal like this, but it was named after the Meuse River which runs through Northern Europe close to Maastricht.

This sea faring animal was very much the top predator of its day, reaching up to 15.2 metres long and weighing 15 tons. While there were other formidable hunters around (one example being Xiphactinus, a 5 metre long predatory fish known for swallowing prey whole!) there was no other marine predator that could rival it. Mosasaurus was an opportunistic hunter, eating almost anything that it could fit its powerful jaws around. This included a whole range of marine animals, from fish to squid, other marine reptiles and even smaller species of Mosasaurs! Mosasaurus was also quite different from other marine reptiles in that its lizard ancestors took to the water at a much later date than other marine reptiles such as Ichthyosaurs and Plesiosaurs. Also, unlike its lizard ancestors Mosasaurus gave birth to live young instead of laying eggs (just like modern day sea snakes). However Mosasaurus, along with the rest of its family, could not survive the asteroid that struck the earth 65 million years ago, dying out alongside the dinosaurs. They are survived by their closest living relatives; monitor lizards and snakes. Which funnily enough makes the sea serpent comparison even more fitting!

The fossilised head of Mosasaurus, showing its frightening battery of teeth!
Image Credit: Tim Evanson,

In the last couple of years Mosasaurus has been getting attention both in film, where it steals the show in the film Jurassic World, and in the world of paleontological research. This research has changed our understanding of how Mosasaurs both looked and behaved, with the following three studies being particularly insightful:

First. A study carried out by Johan Lindgreen, Hani Kaddumi and Michael Polycin in 2013 discovered a new anatomical feature in Mosasaurs. Previously it had been thought that they powered their long bodies through the water with a broad, straight tail, moving in a undulating manner like a modern day sea snake. However, after examining a fossil Mosasaur, named Prognathodon, from Jordan in Africa the palaeontologists noted that the outline of its skin had been fully preserved. This impression clearly showed a tail fluke like those of sharks or Ichthyosaurs, albeit with the upper fluke being smaller than the lower fluke. This tail, a product of convergent evolution, would have enabled mosasaurs to perform fast, powerful strokes to catch prey by surprise.

Second. A study in 2014, carried out by a team of palaeontologists based at Lund University in Sweden (which also included Lindgreen and Polycin, among others), gave us our first look at the colour of a mosasaur. This was an exciting find as evidence of colour is very rarely preserved in extinct animals and had never before been seen in a marine animal. The study looked at tiny blob like structures on the skin of an 85 million year old fossil mosasaur named Platecarpus tympaniticus. These had previously been thought to be bacteria. However as it turns out these blobs were actually melanosomes, the cells that produce skin colour. The structure of these preserved melanosomes showed that this mosasaur, and by extension other mosasaurs such as Mosasaurus, had what is known as “countershading”. Countershading is a colouration pattern that consists of a dark upper body and a light lower body (an example of this being the colouration of a modern day Killer Whale). This has a few advantages; it provides camouflage against the dark ocean depths (when looked at from above) and against the sunlight lit surface (when looked at from below). The dark upper surface also allows the mosasaur to absorb more heat from the sun when it surfaces for air and gives it protection from UV light when at the surface.

Third. A recent study conducted at the University of California, and only published in September 2019, looked in detail at how Mosasaurs swam. What they found was that Mosasaurs could perform a “breaststroke” like action with their front flippers. In conjunction with powerful beats of their tails, this would have allowed them to achieve great bursts of speed through the water. This is interesting because it was thought that marine animals swim using either their tails or their fins, but not both at the same time. As a result this swimming style is unlike any other known animal and makes mosasaurs even more remarkable.

And so, thanks to studies both old and new, we have a detailed picture of Mosasaurus, and its family, as one of the most unique sea faring animals ever. It further proves that the world of paleontological research is still capable of putting fresh spins on iconic animals of the past!

Mosasaurus enjoying a dinosaur dinner!
Image Credit: Jonagold2000,

References/Further Reading

Lindgren, Kaddumi & Polcyn 2013 paper about Mosasaur tail flukes.

Lindgren, J., Kaddumi, H. & Polcyn, M. Soft tissue preservation in a fossil marine lizard with a bilobed tail fin. Nat Commun 4, 2423 (2013).

Lindgren et. al. 2014 paper about Mosasaur coloration. This study also discovered the colour of a 55 million year old turtle (which had the same colour as a modern day leatherback turtle) and a 200 million year old Ichthyosaur (which was a dark colour).

Lindgren, J., Sjövall, P., Carney, R. et al. Skin pigmentation provides evidence of convergent melanism in extinct marine reptiles. Nature 506, 484–488 (2014).

A paper, written by Kiersten Formoso and published in September 2019 (Formoso 2019), on new theories on Mosasaur swimming motions.

Formoso, Kiersten K., Reassessment of the Mosasaur pectoral girdle and its role in aquatic locomotion, Geological Society of America Abstracts with Programs. Vol. 51, No. 5, (2019), doi: 10.1130/abs/2019AM-333823

Further information, from the FossilEra website, about Mosasaur size, diversity, lifestyle and history of discovery

FossilEra “Mosasaurus & Mosasaurs”, FossilEra,

Is it a shrimp?! Is it a jellyfish?! No its Anomalocaris!

Science is not always static. Like any living species that has, currently or will exist it is constantly changing over time, with scientific theories evolving to fit the best available evidence. This phenomenon is prevalent throughout the scientific world but one area where it can be very clearly seen is in Palaeontology, where there are many instances of reconstructions of extinct life being very different in the past than they are today. One example of this is Megalosaurus, one of the first dinosaurs to be properly described by science. The original Victorian interpretation can be seen in a full scale model at the Crystal Palace in London. It is an impressive sculpture of a big hulking four legged lizard, portrayed as the Victorian scientists interpreted it, however it is nothing like the more graceful reconstruction nowadays. Another example, whose outdated model can be seen in the Sedgwick Museum in Cambridge, is the Carboniferous arthropod Megarachne (“Great Spider”). Once thought to be the largest spider that ever lived new research in 2005 found it to instead be a small to medium sized species of freshwater sea scorpion (though in my opinion this doesn’t make Megarachne any less unsettling to look at!)

However one of the most interesting cases of an extinct animal whose palaeontological reconstruction has changed greatly over time with new discoveries has to be Anomalocaris, whose name means “unusual shrimp”. Anomalocaris lived approximately 505 million years ago during the Early-Mid Cambrian. The Cambrian, from an evolutionary perspective, was prehistories equivalent of the European Renaissance of the 15th century. New body plans and weird evolutionary experiments were emerging during this period of earths history. Some animals from this time became extinct not long after they appeared. Some, like the trilobites, survived for an amazingly long period of time (trilobites appeared 520 million years ago in the Early Cambrian and went extinct during the Late Permian 250 million years ago – a longevity of 250 million years!) While others would eventually evolve and diversify into the main animal groups alive today; including the vertebrates which humans are a part of.

Anomalocaris is one of these weird wonders. It was discovered in 1892 by Joseph Frederick Whiteeves in the Burgess Shale formation, a fossil lagerstätten (which is a site where a high concentration of fossil material is preserved due to special environmental conditions) in Canada. The original fossil, named Anomalocaris canadensis, looked like a shrimp but with no clear headparts, hence its name of “unusual shrimp”. For a long time Anomalocaris was only known from this basic description and while it was definitely strange, its lifestyle was a complete mystery. Nineteen years later in 1911 the palaeontologist Charles Walcott, who is famous for his extensive work on the Burgess Shale, discovered a fossil of what seemed to be a primitive jellyfish. He gave it the name Peytoia nathorsti. Later, in 1928, Laggania cambria was discovered; the name given to a long bodied fossil that was interpreted as a relative of sea cucumbers.

Now you may be wondering “I thought you were going to be talking about Anomalocaris? Why have you wondered off topic to these random animals?” Well this is where the story gets interesting! In the early 1980s, nearly 90 years after Anomalocaris was first named, a palaeontologist working at the University of Cambridge by the name of Harry Whittington, an expert in Cambrian arthropods of the Burgess Shale, saw something that was truly astounding while preparing a fossil from the Burgess Shale. As he chipped away at the rock he saw two Anomalocaris “shrimps” attached to the head of a larger body not too dissimilar to Laggania. Not only that but a Peytoia fossilwas found to be attached to this same head. It soon became clear that Anomalocaris, Peytoia and Laggania were not separate species, but all part of one huge Cambrian animal, which was given the name Anomalocaris as that had been the original fossil part that had been found.

Anomalocaris was the top predator of its day. At around a metre in length it was the largest single animal the earth had ever seen at that point. After identifying its prey using large compound eyes, which gave it excellent eyesight comparable to modern day insects, it then used its prongs, once thought to be shrimps, to grab and hold its prey. Anomalocaris then held the prey close to its mouth-parts, once thought to be Peytonia, so the mouth parts could rip and break through the hard exoskeletons of trilobites and the soft bodies of other Cambrian arthropods that made up its prey. Anomalocaris swam via undulatory movements of their regularly arranged horizontal side flaps in the same manner that modern day soft bodied marine invertebrates do today. Anomalocarids as a group were widely successful, ranging across the globe from Canada to China and living from the Early to Middle Cambrian period. While most Anomalocarids were predators, another species has been described relatively recently in 2014 and named Tamisiocaris borealis (“sieve shrimp”). It had a very different lifestyle to Anomalocaris, possessing bristles on its prongs which it’s thought to have used in filter feeding, behaving rather like the baleen whales of today. This makes Tamisiocaris the earliest example of a large filter feeding animal known to science.

So Anomalocarids, the weird shrimps of the Cambrian, really are a fascinating group of arthropods. Once thought to be multiple separate animals, Anomalocaris and other Anomalocarids have instead been shown to be one of the weirdest of all Cambrian animals, and a true example of the evolutionary variety that has evolved on this planet.

The strange shrimp itself
Image credit: UNE photos,

EDIT: In this blog I state that Anomalocaris could “rip and break through the hard exoskeletons of trilobites”. This is actually wrong! A study in 2010, led by James Whitey Hagadorn from the the Denver Museum of Nature and Science, used 3-D models of Anomalocaris‘ mouth-parts to show that (a) it couldn’t close its mouth the whole way and (b) its mouth was too delicate to crush hard exoskeletons. As a result Anomalocaris would have fed mostly on soft bodied animals, and maybe even trilobites that had just moulted (and therefore had softer shells).

References/Further Reading

A blog, written by Ed Yong and published in Discover Magazine, about Anomalocaris

Yong, Ed, “The sharp eyes of Anomalocaris, a top predator that lived half a billion years ago”, Discover, Dec. 7, 2011,

The official Burgess Shale website page about Anomalocaris

“Anomalocaris canadensis”,

Vinther et. al. 2014 paper, published in the journal Nature, on the filter feeding Anomalocarid Tamisiocaris

Vinther, J., Stein, M., Longrich, N. et al. A suspension-feeding anomalocarid from the Early Cambrian. Nature 507, 496–499 (2014).

A wired article talking about the Hagadorn 2010 study that showed that Anomalocaris couldn’t eat hard bodied prey (USED FOR THE EDIT)

Mosher, Dave, “Giant Vicious-Looking Ancient Shrimp Was a Disappointing Wimp”, Wired, Mar. 11, 2010,

Original Hagadorn study: Hagadorn, J. (2010). Putting Anomalocaris on a soft-food diet. 2010 GSA Denver Annual Meeting.