Paleo Profiles: Elasmotherium

Reconstruction by W.S. van der Merwe

The Ice Age has become synonymous with larger than life woolly animals ranging from the Megaloceros, a deer with antlers the same length as a human is high, the woolly rhino Coelodonta, and the famous woolly mammoth. However, another woolly rhino roamed the plains of Ice Age Eurasia - the Elasmotherium. Often called the 'Siberian Unicorn' for its long horn the Elasmotherium is one of the many unique animals to roam the Ice Age world.

Discovery and Fossils

A skeleton at Azov History, Archaeology and Paleontology Museum-Reserve

The Elasmotherium was first described at the start of the 1800s by a Russian/German palaeontologist called Gotthelf Fischer von Waldheim. The fossil had been owned by a close friend of Catherine the Great, Yekaterina Dashkova, who donated it to the Moscow University in 1807, so Waldheim described it the following year. He named the fossil Elasmotherium sibericum - Thin Plate Beast from Siberia. Since then, many more fossils of this extinct rhino have been found across Eurasia, ranging from Siberia and China in east Asia all the way up to Ukraine in eastern Europe. A second species of Elasmotherium was discovered in 1914 by another Russian palaeontologist Aleksei Borissiak in the Caucasus region along the Black Sea - this new species was far older and was named Elasmotherium caucasicum. Research in the early-2000s found that some of the fossils assigned to the Caucasus species was in fact that of a different species of Elasmotherium - this new species was named Elasmotherium chaprovicum. As the Elasmotherium went extinct relatively recently in the history of the planet palaeontologists have recently managed to take DNA samples from fossils, something which allows us to know that Elasmotherium was on the rhino evolutionary tree, and we may even have cave art. Art by our ancestors can give palaeontologists good insights into how prehistoric animals looked and acted. Rouffignac Cave in France depicts a wide range of now extinct animals, mostly mammoths, but one has puzzled archaeologists. One seemed to be a one-horned rhino, but the Coelodonta, known to live in the area and alongside humans, had two horns. Although it can easily be a Coelodonta with artistic licensing, it could also be an Elasmotherium possibly showing that people in France somewhat knew about the Elasmotherium.

When and Where

The distribution of fossils by Schvyreva

The genus of Elasmotherium first appeared in the Pliocene about 2.5 million years ago - these fossils were from the caucasicum and chaprovicum species. Eventually these two species would go extinct, and they evolved into the better known Elasmotherium sibericum. Recent research has revealed an interesting aspect of when the Elasmotherium went extinct. Traditionally, it has been believed that the Elasmotherium went extinct sometime between 200,000 and 100,000 years ago during an epoch known as the Pleistocene. As this was many thousands of years before the large-scale Pleistocene Extinction, caused through a mixture of climate change and human activity, for sometime it was believed that it was a victim of 'natural extinction'. This is when a species naturally goes extinct, and a new species evolves to fill the vacant ecological role left behind. However, research done on 23 fossils in 2018 found that Elasmotherium managed to survive until a long time after this date. Through radiocarbon dating it has been found that they managed to survive in what is now Kazakhstan until as recent as 39,000 years ago. Elasmotherium was found from eastern Europe all the way up to Siberia at their height, so this Central Asian population represented the last of the rhinos. 

Biology

A possible depiction in Rouffignac Cave

Unlike the better known woolly rhino, there has been many debates about the biology of the Elasmotherium. The big issue is its horn. You will often see this rhino recreated with one big horn, earning it the nickname of 'the Siberian unicorn'. However, there is an issue with this - we don't actually know if it had a horn. Rhino horn is made of keratin, the same material which our nails and hair is made of, which does not preserve as easily as bone, so few Elasmotherium horn has been preserved. It is more than likely that it did have a horn, especially as other Pleistocene rhinos had horns. Now that DNA analysis has found that Elasmotherium is indeed in the same family as modern rhinos, it is certain that they had a horn. Another question then arises, what did the horn look like? Rhino horns can look very different species to species, and one hypothesis is that each Elasmotherium species had a horn looking different to others. This is especially the case as the early species lived alongside one another; the shape of the horns could be a quick way to differentiate between the two species. All of them likely would have thick muscles around the shoulders so they could lift up their heads.

Another debate is whether Elasmotherium had thick fur. A paper from 1878 has claimed that they did comparing them to 'contemporary rhinoceros and mammoth'. However, this is based on an idea that the Ice Age was a continuous period of icy coldness - instead there were glacial periods which moved between periods of warmth and bitter cold. It is quite likely that during the warmer periods they would have had thinner layers of fur, which gave way to thick shaggy fur during the cold periods. The Siberian cold was also dry, so a thick layer of fur could better trap in the heat. Unlike other rhinos, the Elasmotherium had quite long legs, so it is quite possible that they stood more upright, similar to horses, than other rhinos. This has led to some off reconstructions like the one below:

The reconstruction by Heinrich Harder, c.1920

It is likely that Elasmotherium moved like a modern bison. Its head close to the earth grazing, with long legs allowing it to run fast. For this reason, it is possible that it could gallop at quite fast speeds.

Diet and Habitat

Isotope analysis has allowed us to know what the Elasmotherium ate. High levels of certain compounds indicate that they would have eaten tough grasses, and this is further shown by their teeth. Their teeth have deep roots, and fossilised teeth show indication of continuous wear. If you see how a modern white rhino eats this is how the Elasmotherium would also eat. They were perfectly adapted to their particular environment. Just like today, large areas of Ukraine, Siberia, and Central Asia are grasslands with nothing to see for miles, something which gets covered in snow during the winter. Elasmotherium had wide feet which would allow them to wade through snow, and their big horn would also be useful to move snow so they could access the grass beneath. Due to the low nutrition in tough grasses, and based on how rhinos claim wide areas as their territory, an Elasmotherium would actually be a fairly rare sight. A solitary life to monopolise access to grass, only meeting up to mate. Other animals would have lived alongside this rhino. Looking at fossils from eastern Europe dating from around 200,000 years ago, A.K. Schyreva has shown that they would have lived alongside now extinct camel and bison species, early mammoths, saiga antelope, and the giant antlered Megaloceros. The later ones would have also lived alongside the famous woolly mammoth, and most likely humans. Some fossils have been found in Italy, and possible presence in cave art meant that humans could have also lived alongside them.

Extinction

Skeleton Reconstruction, photo can be found here

Now that we know that Elasmotherium went extinct around 39,000 years ago we can put them as one of the casualties of the Quaternary extinction event. Beginning around 130,000 years ago the peak of the extinctions occurred between 12-8,000 years ago, but it is important to remember that the Elasmotherium was limited to a smaller area by 39,000 years ago. At this time cooler temperatures started chaging the environment, and the grasses which the rhinos grazed on gave way to lichens and mosses. Especially as more herbivores could eat these plants, it meant that the rhinos suddenly had far more competition, on top of their primary food source becoming depleted. As expected, humanity sealed the deal. As humans started moving into areas inhabited by Elasmotherium they would start hunting them. Consequently, the struggling pockets of rhinos would be pushed into extinction - a tale unfortunately all too common.

The sources I have used are as follows:

-A.K. Schyreva, 'On the importance of the representatives of the genus Elasmotherium (Rhinocerotidae, Mammalia) in the biochronology of the Pleistocene of Eastern Europe', Quaternary International, 379, (2015), 128-134

-'The Elasmotherium', Nature, 18:458, (1878), 387-389

-Pavel Kosintsev, Kieren J. Mitchell, Thibaut Devièse, Johannes van der Plicht, Margot Kuitems, Ekaterina Petrova, Alexei Tikhonov, Thomas Higham, Daniel Comeskey, Chris Turney, Alan Cooper, Thijs van Kolfschoten, Anthony J. Stuart, and Adrian M. Lister, 'Evolution and Extinction of the giant rhinoceros Elasmotherium sibiricum sheds light on the late Quaternary megafaunal extinctions', Nature, 3, (2019), 31-38

-'Elasmotherium', Prehistoric-Wildlife.com, [Accessed 31/01/2020]

-Josh Davis, 'The Siberian unicorn lived at the same time as modern humans', Natural History Museum, (26/11/2018), [Accessed 31/01/2020]

Thank you for reading. For other Paleo Profiles we have a list here. For other blog posts please see our Facebook or catch me on Twitter @LewisTwiby.

Paleo Profiles: Megatherium

A Megatherium, from the London Natural History Museum

Visitors to the Natural History Museum in London in the second half of the nineteenth century gasped in awe upon seeing a giant skeleton. Visitors today may do so at the animatronic Tyrannosaurus, the long-necked sauropod Camarasaurus, or perhaps Dippy, the Diplodocus who until recent years dominated the Entrance Hall. However, in the 1800s the guests were not gasping at a dinosaur as they would today - instead they were in awe of a sloth. The Megatherium was one of the largest mammals to ever walk on land; only the largest of mammoths, elephants, and the great Paraceratherium exceeded it in size. 

Discovery and Fossils

Megatherium has been known to science for a long time - long before science officially described dinosaurs. In 1788 on the banks of the Lujan River in Argentina Manuel Torres came across several large bones which were then shipped to Madrid where they were stored in the Museo National de Ciencias Naturales. This coincided with the European Enlightenments which have been seen as one of the intellectual movements which gave rise to present-day science. As a result, anatomists and early biologists were eager to examine newly found bones, and live specimens. Eventually, an anatomist named Georges Cuvier - a French anatomist and biologist who would be considered to be a 'founding father' of palaeontology. Looking at the bones he described them as resembling that of a sloth - originally he even stated that, like sloths, it lived in the trees - except that these bones were from an animal the size of an elephant. His paper in 1796 named this extinct animal Megatherium americanum, 'Giant best from America'. Cuvier continued studying Megatherium eventually changing his mind on the sloth's biology; he argued it really lived a subterranean life using its big arms and claws to dig tunnels. He was half correct; Megatherium could dig but it did not lead a subterranean life.

Georges Cuvier

We have many examples of Megatherium fossils from across South America. It was an incredibly diverse animal having eight different species which occupied all of the continent from Patagonia in the south to Colombia in the north. Close cousins of the Megatherium also dominated the southern US and Central America as well. Normally, palaeontologists have to deal with a few remains and, therefore, have to reconstruct animals from better preserved relatives or logical guesses. The number of complete skeletons we have of Megatherium means that we do not have that issue in this case.  On his voyage with the Beagle Charles Darwin even brought some skeletons back with him in the 1830s. Other genus of ground sloths have even given us fossilised hair and droppings which paints a better picture of what the Megatherium was like in life. 

Biology

The size of the Megatherium from Prehistoric-Wildlife.com

The ground sloths share a basic body shape with their relatives in the trees, except that their bodies have adapted for life on the land instead. The hind legs are short with the lower bones being as thick as the femur; they had short but thick tails; robust bones; a broad pelvis; and a low body - this allowed the Megatherium to eat from the trees while remaining firmly on the ground. A stable lower-body allowed the sloth to raise itself onto two feet to browse from the trees. Its upper body was surprisingly flexible to reach branches; prehensile lips (with a possible prehensile tongue) to choose the best foliage; and strong, muscular jaws to effectively cut through the vegetation. As this animal was feeding it would rear up, using its tail as a tripod to steady itself, and then use its arms and lips to physically feed. The Megatherium's hands were also decked out in five curved claws which could be up to 70-cm (around 2.4-foot) in length. These could be used to tear leaves from the trees or bend branches closer to its mouth - or alternatively be used as a weapon. Megatherium would have walked on all-fours, but from footprints we know that it could spend considerable amounts of time in a bipedal stance. Even when on all-fours it had a unique way of walking; to protect its claws from unnecessary wear it would walk on the sides of its feet. Pictured below is a relative of the sloths - the giant anteater. Like the Megatherium they are heavily reliant on their claws so when they walk in a quadrapedal stance they do so on their knuckles.

A giant anteater walking on its knuckles, from Arkive by Joe Kolowski, Accessed 05/01/2019

Megatherium was in the Order Pilosa which included other giant ground sloths, and today is comprised of modern sloths, anteater, and tamanduas. Expanding it out slightly they also belong to the Superorder Xenarthra which also includes armadillos - the giant armadillo even walks like a ground sloth. The Megatherium differs thanks to its size - the largest were 6 metres long (20 foot) and weighed up to 4 tonnes. Modern elephants are of an equivalent size. A lot of this came from the animal's bones and muscles - it was big to make itself stable. As a result, adult Megatherium had little to fear in regards to predators. However, due to its size, weight being at the lower half of the body, and walking style this made Megatherium a slow animal.

When and Where

An example of the Great Interchange, Wikipedia - the blue originated in the North, the olive the South

One of the reasons why we have so many Megatherium fossils is due to it living quite recently. Megatherium first appeared in the early Pliocene, sometime between 5 and 3 million years ago, or when humanity's first ancestors started becoming bipedal. Megatherium's ancestors evolved during a time of great change. Moving continents lead to the creation of the Isthmus of Panama bridging the gap between North and South America. This severed the link between the Atlantic and warmer waters leading the Atlantic, and also the Arctic and Antarctic, to become much cooler. Two continents now being connected allowed animals to migrate: deer, camelids, and big cats were just some who moved south as sloths, giant terror birds, and hummingbirds were just some who moved north. Hence, we have sloths closely related to Megatherium living in Central and North America. The Eromotherium was so similar to Megatherium that it was once, and sometimes still is, classed as Megatherium. As giant ground sloths existed in woodlands and grasslands this have them a wide area to call home - we have found Megatherium for that reason in nine countries, the most recent being found in the Peruvian Andes. Existing throughout the Ice Age it managed to last until the last few thousand years. We can even carbon date the youngest Megatherium fossils, and the giant sloths went extinct around 8,500 BCE.

Diet

Like existing sloths Megatherium was adapted to eating plants. Their jaws were adapted to slice through thick foliage allowing them to browse from the trees as well as through various grasses and agaves found in America's grasslands. Most of this is not speculation either. Fossilised dung from Megatherium and other ground sloths have shown us their diets - inside the fossilised droppings we find a wide variety of plants, in one up to over 70 different types. However, Richard Fariña and Ernesto Blanco have put forward a controversial theory: Megatherium could be an omnivore. They argued that short triceps meant that Megatherium could move its arms quickly making its claws an effective weapon. They did stress that Megatherium was not a hunter - instead, using its immense size, it would scare predators from their kills to supplement their diets. The BBC documentary Walking with Beasts portrayed it as doing exactly that. This theory has been criticised in recent years. Palaeontologists have pointed out that we likely would have found claw marks from sloths or evidence in dung if meat was such a large part of their diet to be classed as an omnivore. Zoologists have found deer eating baby birds in the wild and hippos even cannibalising one another so it is not too far-fetched for Megatherium to occasionally scavenge. Undoubtedly, the Megatherium would almost entirely be herbivorous.

Habitat

A Megatherium in its habitat in Walking with Beasts

Megatherium lived in the grasslands and woodlands across South America - imagine llaneros herding their cattle today and coming across a giant ground sloth. Their bodies being adapted to an occasional bipedal lifestyle would indicate that woodlands, or the outskirts of woodlands, would be the ideal habitat for a Megatherium. They would live alongside a wide variety of fauna including the lama like Macrauchenia, a giant armadillo (the size of a small car) with a clubbed tail called Doedicurus, the terror birds (two metre tall predator birds), and the Smilodon, better known as the sabre-toothed cat. A fully grown Megatherium would have no fear, other than other sloths, but younger ones would have potential predators. Smaller ground sloths, although still fairly large, in North America have been found to have dug holes. This could be a potential way to clean themselves - dirt baths are particularly effective way to clear fur from ticks - but also a potential place to hide from a predator. They likely had one predator: humans.

Extinction

Megatherium is one of the first animals lost in the Sixth Mass Extinction - the mass extinction caused by humanity. When humanity expanded into Europe, Australasia, and the Americas most of the megafauna went extinct - including the giant sloths. We even have fossil evidence to show that humans did hunt smaller cousins to the Megatherium - cuts and breaks on sloth bones show evidence that humans had used their bodies for resources. It is quite likely that Megatherium could have met the same fate. One theory has suggested that humans accidentally caused a mass extinction as fauna went extinct thanks to disease introduced by domesticated animals. However, humans were not the only reason why the sloth went extinct. From around 12,000 years ago the climate started rapidly changing - which has been suggested why humanity adopted farming - which drastically affected habitats worldwide. Climate change had restricted Megatherium's habitat which started driving the sloth into extinction - human hunters ensured that it did go extinct. Megatherium was joined in extinction by the rest of the ground sloths as well as much of the megafauna of the Americas.

Thank you for reading. The sources I have used are as follows:

-'Megatherium', Prehistoric-Wildlife.com, (Accessed 04.01/2019)

-Jeremy Green and Daniela Kalthoff, 'Xenarthran Dental Microstructure and Dental Microwear Analyses, with New Data for Megatherium americanum (Megatheriidae)', Journal of Mammology, 96:4, (2015), 645-658

-Gideon Mantell, 'The Megatherium', Scientific American, 37:7, (1852), 291

-'Sabre Tooth',Walking with Beasts, (2001), BBC, 13 December

-M. Susana Bargo, 'The ground sloth Megatherium americanum: Skull shape, bite forces, and diet',  Acta Palaeontologica Polonica, 46:2, (2001), 173-192

-Francois Pujos, 'Megatherium celendinense sp. nov. from the Pleistocene of the Peruvian Andes and the phylogenetic relationships of Megatheriines', Palaeontology, 49:2, (2006), 285-306

-Pip Brewer, 'What was Megatherium?', Natural History Museum, (22/11/2018), Accessed 04/01/2019
-Tim Haines and Paul Chambers, The Complete Guide to Prehistoric Life, (London: BBC Books, 2005)

Thank you for reading. For other Paleo Profiles we have a list here. For future blog updates please see our Facebook or catch me on Twitter @LewisTwiby.

Paleo Profiles: Megalodon

The jaws of megalodon in the American Museum of Natural History

Welcome to our first Paleo Profile! As mentioned in our Introduction I am not a palaeontologist but rather a palaeontology enthusiast so this is not going a more authoritative look at the past. Anyway, with that out of the way we can jump right in. Millions of years ago a monster swam through our oceans which dwarfed the great white shark. This monster was a shark which fed on whales: Megalodon. O. megalodon has become well renowned across the world for its giant size earning it a place in the media whenever a giant shark is needed. As I am currently writing a new blockbuster called The Meg has a megalodon as the creature hunting down and eating swimmers. Often overlooked is that megalodon, despite its immense size, was a real creature, just as real as the great whites and tiger sharks which stalk the world's oceans today.

Discovery and Fossils

A megalodon tooth next to a banana for scale

Megalodon has been somewhat known by people for centuries but not in the way that you would imagine. The giant teeth of megalodon, and other large sharks, would be found by people who assumed that they were the petrified tongues of dragons. This was a regular occurrence with fossils - ammonites at one point were believed to be petrified snakes turned to stone as punishment from God for tricking Adam and Eve, and some less scrupulous individuals would carve snake heads onto them to trick buyers. It would take until 1667 when Danish naturalist Nicolas Steno in The Head of a Shark Dissected correctly identified the teeth as belonging to a large shark, but it would take a lot longer for the shark to be described. By the 1800s palaeontology was emerging as a new field of study as naturalists started realising that some of the skeletons they had been discovering were not just larger variants of extant animals. Sometime before 1837 Swiss naturalist Louis Agassiz described the shark who the teeth belonged to, but it took until 1843 for him to formally describe the shark. He named it Carcharodon megalodon - Carcharodon being the genus which the great white belonged to and megalodon meaning 'big tooth'. However, an different naturalist, Edward Charlesworth, in 1837 (citing Agassiz) called it Carcharias megalodon. This will become important later on.

We have a lot of specific fossil evidence of megalodon and most of it happens to be the teeth of the shark. Sharks can go through up to 40,000 teeth throughout their life and megalodon was no exception to that. Naturally we have lots of teeth believed to be from megalodon. It is a misconception though that we only have teeth from the shark, in reality we also have vertebra from megalodon. Unlike the rest of a shark's skeleton, made from 'soft' cartilage, the vertebrate is made of harder calcified cartilage which is more likely to be fossilised.

What type of shark is megalodon?
You may be wondering why within a few years Carcharodon and Carcharias were used for megalodon within a space of a few years. Originally it was believed that megalodon was an extinct larger great white as they were, and are, large predatory sharks and that they had similar teeth. However, the only similarity is that they are triangular and serrated, on closer look you notice more differences. Among these is that great whites have thinner teeth for their size compared to megalodon. As a result palaeontologists started suggesting that megalodon belonged to Carcharias instead where both sharks shared a common ancestor with some palaeontologists also suggesting that megalodon was a transitional fossil between older shark groups and the modern great white. There was some pushback to the transitional fossil theory as great whites lived alongside megalodon but it has been pointed out that transitional fossils can live alongside their later relatives, as shown with the Smilodon (sabre-toothed cat) whose species lived at the same time. However, other megatooth sharks were discovered and in 2012 an extinct relative of great whites was discovered showing a closer relation to makos than megatooths. As a result the megatooths were assigned the genus Carcharias. Our story does not end here. One family of shark yet to be mentioned are the Otodontids (now extinct). The Otodontids, of which Otodus was the most famous genus to comprise it, were closely related to Lamnidae, which the great white belongs to. Through research palaeontologists now believe that Carcharias is no longer a valid genus and that megalodon is really a species of Otodus with great whites sharing a common ancestor, and therefore being more closely related, with the mako shark. The reason for the similarity between great whites and megalodon is believed to be convergent evolution - the same way in how birds and bats fly despite having no shared ancestors. Hence, it is now Otodus megalodon instead of Carcharodon or Carcharias megalodon.

Biology

The size of megalodon from Prehistoric-wildlife.com

The reason why megalodon is so famous is because of its size. The issue is we have no idea how large the megalodon really was with estimates ranging from 15 metres long at its smallest to 20 metres at its largest (just ten metres shorter than the largest blue whales) - in contrast the largest great whites are just under 5 metres and the fictional shark from Jaws is almost 8 metres. Regardless of its size megalodon was a giant. How did they get these sizes though? In 1973 John E. Randall used the height of tooth enamel to give a size of 13 metres which was seen as inaccurate as he based this method on using white shark teeth and although similar they were very different. Even then enamel can have different thickness tooth to tooth never mind between individual animals thanks to wear, (and also preservation). In 1996‭ Michael D.‭ ‬Gottfried,‭ ‬Leonard J.‭ ‬V.‭ ‬Compagno and S.‭ ‬Curtis Bowman decided to measure the length of the cutting length of the tooth which gave an estimate of 19 metres, and in 2002 Clifford Jeremiah used the width of the tooth to find the width of the jaw and from there got an estimate of 15.5 metres. The same year Kenshu Shimada using a tooth from Panama used the tooth crown to get an estimate, seen as fairly accurate, of about 15.1 metres. As a result between 15 and 17 metres is seen as megalodon's length. However, sharks are very muscular so with muscles comes weight which is hard to estimate for an animal only known by teeth and some vertebra. Weight does not increase at a constant with length so we have a very wide range of proposed weights ranging from 47 metric tons for at 15.9 metre long shark to 103 metric tons for a 20 metre long one.

Most reconstructions portray megalodon as a massive great white but recently this has changed among paleoartists at least. Mainly this is due to how we now know that it is unlikely that megalodon was in the same genus as the great white. Some have suggested that they would look like a tiger shark as Otodus is thought to resemble tiger sharks but again this is seen as unlikely. Megalodon lived like a great white so it is quite likely that at a glance they would look similar - animals which evolved to fill similar niches often resemble one another. However, there would be noticeable differences. For example, the jaws would have thicker and the shark overall would appear thicker itself as it would need to be in order to power such a long body. The megalodon would have fairly long fins, particularly the tail fin, in order to reduce drag while swimming and when you look at the fins of whales, tuna and large sharks like whale sharks they are long for this reason. Below is a photo of a whale shark which shows just how big their fins can get.

As you can see on the photo the whale shark is being followed by smaller fish. Today great whites are also followed by smaller fish like remoras so it is likely that they would follow megalodon as well. It has been suggested that barnacles could even grow on elderly megalodon like on some whales. Megalodon could have an entire micro-ecosystem living around it with fish picking up stray bits of flesh from its last meal, parasites feasting on the shark itself, and also other animals eating the parasites. How did megalodon survive as an animal itself? Megalodon had a high metabolism to power its body and was likely mesothermic meaning that it was both cold and warm-blooded much like tuna and white sharks of today. This allowed it to possibly send warm blood to its head allowing its brain and sensory organs work along warm-blooded metabolic levels. The sheer size of the shark would also allow it to be gigantothermic where, thanks to its size, the outer layers of skin and muscles would insulate the shark. Finally, we have the jaws. Like modern sharks it would be able to move its upper jaw when biting and the bite of a megalodon was phenomenal. In 2008 a computer model was made to estimate the bite force of white sharks which was applied to the megalodon they found out just how powerful its bite was. A 16 metre long shark was found to have a bite force of 108,514 Newtons, or around 11 metric tons, while a 20 metre long shark 182,201 Newtons, or over 18.5 metric tons. That meant that the lower size estimate possibly had a bite force greater than that of a Tyrannosaurus rex! Finally, megalodon is believed to be long lived. Great whites can live to be 75 and generally larger animals live longer than smaller ones so megalodon could possibly live to be a century.

When and Where

The shark's distribution on a modern map from Prehistoric-Wildlife.com

Despite being shown in the media megalodon did not live alongside the dinosaurs. Non-avian dinosaurs (basically dinosaurs which aren't modern birds) went extinct around 66 million years ago and megalodon did not appear until around 23 million years ago in the early Miocene. It lasted a very long time with it going extinct in the Late Pliocene, or more specifically c.2.6 million years ago. To put it in perspective the first members of our genus, Homo, evolved 500,000 years after the extinction of this giant shark. Megalodon was truly the apex predator of the oceans with its teeth being found everywhere from Essex in England, to New Zealand's north island, to Peru and Panama. The only place where it was not known to live in were the waters of the Arctic and Antarctic. Global temperatures were warmer than today so it could survive everywhere and likely competed against white sharks. It has been theorised that white sharks and megalodon would migrate to avoid competing against one another. Even the shallows were not out of bounds. Pups occupied the shallows which brings us to our next point...

Birthing a Monster
Like most modern large sharks megalodon gave birth to live young but we don't know if they grew in an egg inside the mother or if they had no egg and received nutrients via an umbilical cord. Mothers didn't give birth anywhere. They gave birth in shallower and safer water in 'nursery grounds' much like modern sharks. We know where nursery grounds are by higher concentrations of smaller teeth and one key area has been identified by Catalina Pimiento, Dana J. Ehret, Bruce J. MacFadden, and Gordon Hubbell in the Gatun Formation in Panama facing the Caribbean. When megalodon swam the seas the Isthmus of Panama did not yet exist with the Central American Seaway instead taking its place. This area created an area, much like the Sea of Cortez where great whites now give birth, of shallow water safe for young megalodon to grow up in peace from larger predators. Most of the individuals from this area measure between 2 to 3 metres but we don't know if they are born that size or grow to be that size later on. In the nursery grounds the pups would eat anything they could get their jaws on ranging from turtles to cephalopods to smaller cetaceans (whales, dolphins and porpoises) like the tusked Odobenocetops from the shores of what would become Peru and Chile.

Diet and Hunting

A megalodon tooth in the vertebrate of a whale

Like the great white megalodon ate everything despite the stereotype of it only eating whales. They definitely did eat whales; one vertebrate had a megalodon tooth sticking out of it. However, it would not regularly target the large baleen whales; they could do serious damage to a shark making it undesirable to attack one. The megalodon would most likely target sick large baleen whales when the opportunity arose. Smaller whales, such as the 5 metre long Piscobalaena nana, would be the main food source for the megalodon. An orca would be the perfect size for a megalodon although orcas could potentially kill one being intelligent, social, and potentially dangerous cetaceans. Nothing was really out of bounds for a megalodon. Whales, sharks, sea birds, seals, turtles, and even aquatic sloths were on the menu for megalodon and smaller megalodon also could potentially be eaten. Cannibalism is common in many shark species, including the great white, so megalodon could eat smaller ones; the nursery grounds offered protection from adults as well as other predators. Like many predators megalodon scavenged and hunted. Sharks have an incredible sense of smell being able to smell blood from miles away so scavenging could be very easy for a megalodon in theory; other sharks would also be wanting to scavenge from a dead whale. Megalodon would hunt like a great white striking from below - being dark in colouring it would be hard to see them from above. With its powerful tail it could propel itself through the water like a torpedo striking the prey - we have fossil evidence of whales with damaged vertebrates indicating that they had been hit with some force. In particular they would target the rib cage where their strong teeth and jaws could tear through the ribs to get to the delicate internal organs. Even if the shark could not bite the whale it would stun them allowing the shark to take a bite; whales could escape as some have evidence of their ribs and spine healing. With the larger baleen whales the sharks could either hit them with their very strong tail or simply bite chunks out of the whale. It is thought that megalodon needed between 600 and 1200 kg of food a day to survive so hunting was needed more than scavenging.

Extinction
Megalodon was easily top of the food chain and dominated the world's oceans for around 20 million years, so why did it go extinct? The reason for their extinction is key considering that shark populations are dwindling. Climate change led to their extinction. Today climate change is decimating shark populations although human hunting and pollution is making a steady decline caused by human caused climate change turn into a very steep decline. Around 2.6 million years ago global temperatures dropped thanks to the arrival of the Ice Age. The Isthmus of Panama was formed connecting North and South America but also closing off the giant Seaway. As a result currents shifted changing whale migratory routes which in turn deprived megalodon of their primary food source around a major nursery ground. Although megalodon could have adapted to changing temperatures the whales they hunted could not; baleen whale diversity dropped from over 20 genera to just six extant ones. 36% of large sea life went extinct including 55% of large marine mammals, 9% sharks, 43% sea turtles and 43% sea birds. As a result megalodon lost a lot of its food source which was made worse when whales moved to colder climates where the mega shark could not follow. Nursery grounds needed shallow water, like in Panama, which vanished with the dropping of the sea level leaving pups exposed to predators. This was the primary reason although it has been suggested that increased competition sealed their fate. In the final few million years of the megalodon's existence more toothed whales including the giant sperm whale Livyatan and most importantly orcas evolved. Not only were they more versatile than the giant shark but they could bite back. As the great white's diet did not rely so heavily on whales their diet was less affected and their smaller size let them hunt and have nursery grounds closer to the shore compared to their larger cousins. Through all of this what made megalodon so powerful for twenty million years ended up sealing their fate.

Still Alive?

The infamous 'documentary' providing evidence for the shark's continued existence

The Meg and the book it's based on has the megalodon woken from being frozen in prehistoric ice but there are genuine theories that the megalodon exists to this day. These range from cryptozoologists to Young Earth Creationists. Curator of Palaeobiology at London's Natural History Museum sums it up well: No. It's definitely not alive in the deep oceans, despite what the Discovery Channel has said in the past. Mostly as we would see signs of attack on whales as we do with giant squid and where they could safely hide out are cold which is the exact reason why they went extinct to start off with. In 1873 the crew of the HMS Challenger picked up a megalodon tooth which gave an age of 10,000 years when tested in 1959. Did this mean that megalodon at least managed to last until humans started agriculture? The answer is no. Other than it being the only tooth to be found they had tested the tooth for manganese dioxide which is very unreliable. When it was later carbon dated they found it had too little nitrogen to be dated; this meant it was too unstable to be properly dated so it can't really be used to prove that it was from 10,000 years ago. Most 'sightings' of the shark are really misidentified megamouth sharks and younger looking teeth are due to preservation, not age. In recent years the conspiracy of the existing megalodon roared into existence again thanks to a Discovery Channel mockumentary called Megalodon: The Monster Shark Lives. In 2013 Animal Planet made a fake documentary called Mermaids: The Body Found which presented 'evidence' that mermaids existed confirmed by 'scientists' (really just actors) along the lines of What we do in the Shadows or Trollhunter. It was clearly fake but it was convincing - although 17 year old me saw it clearly as being fake I was convinced by some of their evidence - so convincing that people didn't realise it was a fake, especially coming from a respected channel like Animal Planet. Despite criticisms that the channel had not made it clear that it was fake it got many views so their sister channel, Discovery, decided to copy the format. In Mermaids a megalodon was seen eating mermaids 1.6 million years ago (albeit at that time it was thought that the shark existed until 1.8 million years ago) so Discovery chose to use the giant shark for Shark Week. Again featuring actors as scientists it featured a crew being attacked by the shark off the coast of South Africa. Like Mermaids it received criticism for featuring a mockumentary on a factual and reliable channel, and despite disclaimers claiming it was fake those who tuned in late or only saw the advertising thought it was real. Not learning from their mistake the next year the re-aired it with no further disclaimers and even made two more mockumentaries about the shark! Basically, the shark is very much extinct despite best efforts from cryptozoologists, poor dating, and Discovery Channel's marketing team.

Thank you for reading. We now have a list of future Paleo Profiles. The sources I have used are as follows:
-Alberto Collareta, Olivier Lambert, Walter Landini, Claudio Di Celma, Elisa Malinverno, Rafael Varas-Malca, Mario Urbina, and Giovanni Bianucci, 'Did the giant extinct shark Carcharocles megalodon target small prey? Bite marks on marine mammal remains from the late Miocene of Peru', Palaeogeography, Palaeoclimatology, Palaeoecology, 469, (2017), 84-91
-Catalina Pimiento, Dana J. Ehret, Bruce J. MacFadden, and Gordon Hubbell, 'Ancient Nursery Area for the Extinct Giant Shark Megalodon from the Miocene of Panama', PLoS One, 5:5, (2010), 1-9
-Catalina Pimiento and Christopher Clements, 'When did Carcharocles megalodon become extinct? A new analysis of the fossil record', PLoS One, 9:10, (2014), 1-5
-C. megalodon, Prehistoric wildlife.com, Accessed 15/08/2018
-Josh Davis, 'Megalodon: the truth about the largest shark that ever lived', Natural History Museum, (06/08/2018), Accessed 17/08/2018
-Trey the Explainer, 'Paleo Profile - Bunch of Prehistoric Fish', YouTube, (05/12/2017), Accessed 19/08/2018
-Trey the Explainer, 'Paleo Profile - Megalodon', YouTube, (22/06/2015), Accessed 19/08/2018

Thanks again for reading. For future blog updates please catch our Facebook or catch me on Twitter @LewisTwiby. 

Paleo Profiles: Introduction

For years palaeontology has been one of my great loves; so much so that I came very close in doing it as my degree at university. The creatures of the past have wowed peoples worldwide ranging from the monsters of the silver screen in Jurassic Park, Gojira, and The Valley of Gwangi to real life folklore and myths. With Paleo Profiles we look at different extinct animals ranging from dinosaurs to mammoths to giant bugs in order to understand what they were like when they roamed the Earth. This series will hopefully inform readers of the wonders of prehistory (and some more recently extinct forms of life). I also want to prefix this by saying that I am a historian, not a palaeontologist. This is something which is a hobby to me and not my field of study so I am not an authority on palaeontology. The purpose of Paleo Profiles is for me to engage in one of my great loves; for newcomers to palaeontology to find out some interesting information; and for those with an active interest/actual authority to also find out interesting points. For any Paleo Profiles if you feel that I've got something wrong or left something out please tell me and I will add it in. Palaeontology is a constantly evolving and changing field; just as much as archaeology and history. 

We will be forming a list of Paleo Profiles as they are written which you can find here. Those with an interest in history, comic books, and everything related to them please be sure to check out our Facebook or catch me on Twitter @LewisTwiby.

Our first Paleo Profile will focus on a behemoth from the deep...