Pleistocene Project

Elephantidae

Mammoths

All mammoths originate from the African continent. The mammals expanded their territory near the end of the Pliocene, to Eurasia and North America. Furthermore they evolved from leaf eaters with low-crowned teeth into true grazing animals with high-crowned teeth. The mammoth became extinct only 3,700 years ago.

Southern mammoth

• Scientific name: Mammuthus meridionalis
• Diet: Herbivore
• Where: North America and Eurasia
• When: Early Pleistocene (and late Pliocene)

The Southern Mammoth is the most famous mammoth from the Early Pleistocene. He lived in Europe and Asia in the late Pliocene from about 2.5 to 3 million years ago and migrated to North America in the early Pleistocene around 1.8 million years ago. It was the largest proboscidea (elephantidae and several extinct families) that ever lived, with a height of 4 metres. There was a large sexual dimorphism, which means that there were large phenotypic differences between male and female. The southern mammoth has had its habitat in the subtropical biotopes and was, judging from its teeth, a deciduous eater.

Steppe mammoth

• Scientific name: Mammuthus armeniacus/ Mammuthus trogontherii
• Diet: Herbivore
• Where: Northern Eurasia
• When: Middle Pleistocene

The steppe mammoth derives from the Southern mammoth. It is assumed that they were more hairy and had smaller ears to adapt to the colder biotope. The name already indicates that the steppe mammoth lived in dry, cold steppe-areas. Its teeth are more high-crowned than the one of the Southern Mammoth, which makes it more suitable for grinding harder grasses. Another difference between the Steppe mammoth and a mammoth from the Early Pleistocene is the shape of the tusks. The tusk of a Steppe mammoth is spiral-shaped, round and could be as long as 5.2 metres, while those of Southern mammoths were about the same size but more robust and less twisted.

Woolly mammoth

• Scientific name: Mammuthus primigenius
• Diet: Herbivore
• Where: Northern Eurasia and northern North America
• When: Late Pleistocene

 The Woolly mammoth is frequently called the Tundra mammoth and is symbolic for the ice age mammals. The mammal derives from the Steppe mammoth, though it is about a quarter smaller than its ancestors. It is still a mystery where this evolution took place; it could have been on the continental part of Asia, but we do know that its spread was limited to the northern hemisphere. Cold areas like Siberia have made it possible to learn a lot about the mammoths habitat and appearance. In the permanently frozen ground, not only bones were preserved, but also pieces of skin, hair and even intestines with its content.

Columbian mammoth

• Scientific name: Mammuthus columbi
• Diet: Herbivore
• Where: Present United States and to as far south as Nicaragua and Honduras
• When: Late Pleistocene

The Columbian mammoth was one of the biggest elephants that ever lived, with an average height of 3.5 to 4 metres. Contrary to other mammoths, the Columbian mammoth did not have much hair, and must have looked quite a bit like the contemporary elephant. A striking feature was large, partially overlapping tusks. The females lived with their young ones, in herds of up to 20 individuals, lead by one dominant female. Males left the herds when they became adults.

American Mastodon

• Scientific name: Mammut americanum
• Diet: Herbivore
• Where: Alaska to Honduras
• When: 3.7 million years ago until 10.000 years ago

The American Mastodon was the last surviving member of the mastodon family. Although it was a mastodon, it looked just like a woolly mammoth, with lots of shaggy hair and about 3 metres in height. Nevertheless it had critical skeletal differences; their teeth are completely different, the skulls of Columbian mastodons are larger and flatter than those of mammoths and their skeletons are more robust and chunky.

 Hoe Tusker

• Scientific name: Deinotherium
• Diet: Herbivore
• Where: Africa, Europe and parts of Asia
• When: Middle Miocene until the Early Pleistocene

 Hoe tuskers had the body of an elephant but the height of a giraffe. Male hoe tuskers were about 3.5 till 4.5 metres high and weighed  between 5 and 10 tons, with the largest males weighing over 14 tons. The strange characteristic of these heavy mammals were its tusks, because they stuck out of the lower jaw (instead of the chin) and pointed to the ground. We now know that these tusks were used to scratch off tree bark.

 Dwarf Elephant

• Scientific name: Dwarf Elephant (collective term)
• Diet: Herbivore
• Where: All over the world, but mainly on islands in the Mediterranean and the Channel Islands of California
• When: Middle and Late Pleistocene

There have been several types of dwarf elephants, including: Stegodon sompoensis, Elephas falconer and the Elephas Cypriotes.  A dwarf elephant was about one tenth of the size of an average sized elephant today. It is believed that the dwarf elephant fossils found on the Mediterranean islands have come from the continental, straight-tusked elephant. Still there is not one measure of what an actual dwarf elephant was, because each island/area had its own descendants. When the sea dropped dramatically, the islands would become one and the different types of dwarf elephants would reproduce and create a hybrid breed of dwarf elephants. This is why each island had its own unique sub-species.

 Straight-tusked Elephant

• Scientific name: Elephas (Palaeoloxodon) antiquus
• Diet: Herbivore
• Where: Eurasia
• When: Middle and Late Pleistocene

 The straight-tusked elephant was a relatively large, robust mammal; between 3.5 and 4 metres high. The tusks, which could reach enormous dimensions, pointed a little outwards and downwards where they left the skull. His ancestor probably lived on the African continent. During the ice ages he remained in the south, and in warmer periods he moved north. This elephant became extinct during the last glacial.

 Cuvieronius

• Scientific name: Cuvieronius
• Diet: Herbivore
• Where: North and South America
• When: 5 million years ago until 10.000 years ago: Pliocene and Pleistocene

 The Cuvieronius was about 2.7 metres tall and looked like a modern elephant, except for the spiral-shaped tusks. This smallish elephant lived in the woodlands of North and South America. It expanded its habitat to South America during the ‘Great American Interchange’, that connected North and South America  a few million years ago.

Cats

American Cheetah

• Scientific name: Miracinonyx inexpectatus
• Diet: Carnivore
• Where: Plains of North America
• When: Pliocene and Pleistocene

 The American Cheetah was about 170 cm long, 85 cm high and weighed about 70 kg. This means that he was slightly larger than the cheetah today.  It had long limbs, a long tail, a lithe body and a blunt snout. His diet consisted of extinct mountain sheep and extinct horses. He could mainly be found in coastal savannahs, forests with open areas, the Appalachian mountain stream valleys and high mountain meadows/forested and rocky slopes.

Cave Hyena

• Scientific name: Crocuta crocuta spelaea
• Diet: Carnivore
• Where: Eurasia
• When: Middle and Late Pleistocene

 The Cave Hyena was characteristic for its long hind legs and strong jaws with strong teeth. Its long hind legs were more muscular than those of a modern hyena. Cave Hyena’s favorite prey animals were the woolly rhino and the Przewalski’s horse. As the name already predicts, the animal liked to drag its kills back to the caves, with its muscular legs. The dangerous mammals also occasionally attacked the early humans and hominids. Kills partially processed by Neanderthal and then by cave hyena indicate that hyena would occasionally steal Neanderthal kills. Furtermore, the  cave hyena and Neanderthal competed for cave sites as they becamer scarcer with the years.

 Cave Lion

The Cave Lion got its name not because it lived in caves, but due to the fact that most of the remains were found in caves. It was one of the most feared predators of the Pleistocene, especially the late Pleistocene.

 American Lion/ American Cave Lion

• Scientific name: Panthera leo atrox
• Diet: Carnivore
• Where: North America, northern South America
• When: Pleistocene

 The American Cave Lion was about 370 cm long, had a tail of 150 cm and weighed about 400 kg. He was a quarter bigger than a modern lion and slightly larger than the Europasian Cave Lion. This species was a powerful predator and fed on equidae, deer and possibly bait. Like the modern lion, this cat killed its prey by suffocating them or biting them in the neck with its short canine teeth. Its habitat consisted of open country, steppe tundra, mountain conifer and grasslands. Another known fact, is that it ate large animals such as horses, deer, camels, grounds sloths, bison and young mammoths

 European Lion/Eurasian Cave Lion

• Scientific name: Panthera leo spelaea
• Diet: Carnivore
• Where: Europe and North Asia
• When: Pleistocene

The Eurasian Cave Lion was about 300 cm long, which is about the size of a very large, modern lion. The animal was most common during the warmer periods of glacials.

 Marsupial Lion

• Scientific name: Thylacoleo carnifex
• Diet: Carnivore
• Where: Australia
• When: Early to Late Pleistocene (1,600,000 to 40,000 years ago)

 The Marsupial Lion was the largest carnivore mammal to have ever lived in Australia. He was closely related to the wombat and the koala. The ‘murderer’, ‘tormenter’ or ‘butcher’ as it is also called, weighed up to 130 kg, was about 150 cm long and stood about 75 cm tall. It looked like a cat, with strong claws and very powerful jaws. It had a striped back, tufted tail and pointy ears. Though it was not a fast runner, but more an ambush predator, it hunted down fairly large animals like; the hippopotamus-sized giant wombat and giant browsing kangaroos. The extinction of the animal, 40,000 years ago, was caused by humans and the climate change.

Sabre-toothed Tigers

• Scientific name: Smilodon
• Diet: Carnivore
• Where: North and South America
• When: near beginning to very end of Pleistocene

This mammal is named after the extreme length of their maxillary canines. Although the name suggests it is a tiger, the animal belongs to the subfamily Machairodontinae, instead of the Pantherinae (felines), where the actual tiger, lion and jaguar belong to. It had a short tail, powerful legs, muscular neck and long canines. The Sabre-toothed Tiger was more robustly built than any modern cat, comparable to a bear. The jaw of this species were surprisingly weak, because of the space occupied by the canines. These jaw muscles weakened during the evolutions.

 Pachycrocuta

• Scientific name: Pachycrocuta brevirostris
• Diet: Carnivore
• Where: Eurasia and eastern Africa
• When: Middle Pliocene to Middle Pleistocene

The Pachycrocuta brevirostris was largest of the prehistoric hyenas, and is frequently called: the Giant Hyena. It was about 100 cm tall and weighed about 190 kg. this would make it the largest hyena to have ever lived. It was a small-pack hunter of large animals, but it probably preferred to scavenge, because it was a heavyset animal not built for chasing prey over long distances.

Marsupials

Zygomaturus

• Scientific name: Zygomaturus
• Diet: Herbivore
• Where: Australia
• When: Pleistocene

The adult Zygomaturus was about 250 cm long and about 100 cm high, with an estimated weight between 300 to 500 kg. The scientific name refers to the broad zygomatic arches (cheek bones) and the three prominent lobes of the premolar teeth. It had a heavy body and thick legs and is believed to be similar to the modern Pygmy Hippopotamus in both size and build. It is also believed that the animals were partially aquatic like hippos, and that they may have lived in swampy areas near the coast and along river systems, and further inland possibly in small herds. He probably ate reeds and sedges, by shoveling them up in clumps with its two fork-like incisors in the lower jaw.

Thylacoleo

• Scientific name: Thylacoleo
• Diet: Carnivore
• Where: Australia
• When: Late Pliocene until the Late Pleistocene

The Thylacoleo is frequently called: “Pouch Lion”. The Marsupial Lion is also a Thylacoleo. The animal possessed enormous hooded claws set on large semi-opposable thumbs, which were used to capture and cut prey. The long muscular tail was similar to that of a modern kangaroo. Chevrons (specialized tail bones) allowed the animal to tripod itself, so the front legs would be free to grasp and cut.

Procoptodon

• Scientific name: Procoptodon goliah
• Diet: Herbivore
• Where: Australia
• When: Pleistocene

The Procoptodon was a type of kangaroo. It had an unusually short, flat face and forwardly-directed eyes, with a single large toe on each foot. Each hand had two long, clawed fingers that would have been used to bring leafy branches within reach. He was larger than the contemporary kangaroo: up to 2 metres tall (although he could reach branches of 3 metres in height, because of its long fore limbs and tail used as a prop)and up to 200 kg in weight.

Palorchestes

• Scientific name: Palorchestes
• Diet: Herbivore
• Where: Australia
• When: Late Miocene until the end of the Pleistocene epoch

“Ancient leaper or dancer”, is the nicknames of this 2.5 metres long, extinct animal. It was quite an unusual marsupial herbivore with retracted nasal bones on the skull, suggesting that it may have had a small trunk. He used its sharp claws to dig for roots and pull branches towards him, while eating leaves. It may have been the Australian equivalent of the giant ground sloths of the Western Hemisphere.

Giant Wombat

• Scientific name: Diprotodon optatum
• Diet: Herbivore
• Where: Australia
• When: 1.6 million until about 46,000 years ago

Diprotodon means “forward teeth” (‘di’ meaning ‘twice’; ‘proto’ meaning ‘first’; and ‘odon’ meaning ‘tooth’ in Greek). This creature was the largest known marsupial to have ever lived. Its size ranged up to 380 cm long (head-tail) and 170 cm at the shoulder. Their habitats consisted of open forests, woodlands and grasslands, probably close to water sources.

Ungulates

Woolly Rhinoceros

• Scientific name: Coelodonta antiquitatis
• Diet: Herbivore
• Where: Eurasia
• When: Pleistocene

Woolly rhinoceros had two horns. The horns are worn down on the under surface which suggests they were swept back and forth sideways on the ground. This may have been to help clear snow off the grass. The woolly rhino’s closest living relative is the Sumatran rhino

Elasmotherium

• Scientific name: Elasmotherium sibiricum
• Diet: Herbivores
• Where: Eurasia
• When: Late Pliocene and Pleistocene

The Elasmotherium sibiricum was a giant rhinoceros of about two metres high and six metres long. It had a single two-metre-long horn in the forehead, which was used for defense, attracting mates, driving away competitors, sweeping snow from the grass in winter and digging for water and plant roots. It may have weighed up to 5000 kg. Its legs were longer than those of other rhinos and were designed for galloping, giving it a horse-like gait. It was probably a fast runner, in spite of its size. Its teeth were similar to those of horses, and it probably grazed low herbs with its ever-growing high-crowned molars.

Bison

The extinct bison lived in the north of the American continent. Before the native Americans started hunting them, around 100 million bison roamed North America in herds. They stretched as far as the north of Canada and as far south as Mexico. The first region from which the bison disappeared was all areas east of the Mississippi River.

Bison antiquus

• Scientific name: Bison antiquus
• Diet: Herbivore
• Where: North America
• When: Late Pleistocene

The Bison antiques is sometimes called “the ancient bison” and is the direct ancestor of the modern American bison. He came from Asia around 200,000 years ago, during the ice age. The extinct bison was bigger than the modern bison with a height of about 200 cm and weight of 2500 kg. Its horns measured from tip to tip one metre. Its fur coat was also much thicker, since the winters were much older 200,000 years ago. They lived in savannahs and open woodlands and shared the habitat with horses, camels, giant ground sloths and mammoths. Unlike the American Bison that has not much fear to their predators when traveling in herds, the Bison Antiquus had to face predators like the Saber-toothed cat, African Lion and Dire Wolves which were extremely violent.

Giant Bison

• Scientific name: Bison latifrons
• Diet: Herbivore
• Where: North America
• When: Late Pleistocene

It is believed that the Bison latifrons evolved into the Bison antiquus. The megafauna mammal reached a shoulder height of 250 cm, length of 5 metres  and weight of 2 tonnes. This means that it was a giant animal with shaggy front legs and giant horns that spanned over 2 metres. He lived in the plains and woodlands of North America.

Stag-moose

• Scientific name: Cervalces scotti
• Diet: Herbivore
• Where: North America and Eurasia
• When: Middle and early Late Pleistocene

Technically, the Stag-moose wasn’t a real moose, but an overgrown deer, even the largest deer to have ever existed. It had unusually long, skinny legs and elaborate antlers. Like many other extinct animals, the Stag-moose became extinct, mainly due to hominids and climate change.

Camelops

• Scientific name: Camelops hesternus
• Diet: Herbivore
• Where: western North America
• When: Late Pliocene until the end of the Pleistocene

The animal was 215 cm high and weighed almost 600 kg. It is not known whether the Camelops possessed a hump, because soft tissue is often not preserved. It was a habitant of the vast prairies of western North America. The Camelops became extinct around the same time that many other megafauna died out. These included the mastodon, native horses and camelids.

Irish Elk

• Scientific name: Megaloceros giganteus
• Diet: Herbivore
• Where: Eurasia, especially Ireland
• When: Pleistocene

The Irish Elk, also known as the Giant Deer, was characterized by the enormous antlers of the male. The animal stood about 2.1 metres tall at the shoulders and the antlers reached a maximum of 3.65 metres. There are still many unproven theories about the evolution of the males antlers. Some say this was due to sexual selection; males were using them in combat for access to females. It was also believed that the antlers became so enormous, that the Irish Elk could not live a normal life and became extinct. Like many other extinct species, the Irish Elk survived the transitions of many interglacials to glacials and the other way around. It is still a mystery why the animals did not survive the transition from the last ice age to this era.

Megatylopus

• Scientific name: Megatylopus
• Diet: Herbivore
• Where: North America
• When: Miocene until the Early Pleistocene

Its name was synomymized with Paracamelus arenicola. The Megatylopus was a large genus of the family Camelidae (even-toed ungulates). It was a tall animal; it stood around 420 cm tall and had extremely long legs of 210 cm. Most of them weighed over 1500 kg.

Long llama

• Scientific name: Macrauchenia
• Diet: Herbivore
• Where: South America
• When: Late Miocene to Late Pleistocene

Macrauchenia was a long necked, long limbed, 3 toed South American ungulate. An exceptional developed characteristic was its maneuverability. This was discovered because of the structure of its ankles and shins. The animal could change directions effortlessly even at high speed. This was extremely useful, since the Macrauchenia was always at constant threat from predators. The Long llama’s nostrils were actually situated on the top if its head

Auroch

• Scientific name: Bos primigenius
• Diet: Herbivore
• Where: Eurasia and North Africa
• When: Late Pleistocene to Early Holocene

The Auroch was the ancestor of domestic cattle breeds, although it was a larger and wild animal. It is believed that the animal evolved in India, around two million years ago and then migrated into the Middle East, further into Asia and later to Europe. The bull’s coat colour was black-brown with a small light stripe. The colour of the cow was just as the calves’ colour: reddish brown. The animal had horns which were pointed forward and were curved inwards. The udder of the aurochs was small and hardly visible. It ate loads of grasses, grass-like plants, herbs and leaves of trees and bushes. The aurochs lived in herds consisting of cows, calves and young bulls. The animal became extinct around 1600 A.D. with hunting humans as main reason.

Hipparion

• Scientific name: Hipparion
• Diet: Herbivore
• Where: North America, Africa and Eurasia
• When: Miocene until the Pleistocene

The Hipparion evolved 20 million years ago in North America and extended its habitat towards Africa and Eurasia. With the Hipparion, the first step was made towards the modern horse. The main difference was the fact that it had two vestigial toes surrounding the single hooves on its feet. This evolved when the animal migrated from swamps areas to open grasslands. Instead of walking on three toes to have more grip in the loose soil, the Hipparion started walking on its middle toe only. This made it quite a lot easier for the animal to walk and run faster, especially with all the predators in the open areas the herds of Hipparions were an easy prey. The animal was not very large; it reached a maximum height of 140 cm.

Pelorovis

• Scientific name: Pelorovis
• Diet: Herbivore
• Where: Plains of East Africa
• When: Pliocene until the Early Holocene

The Pelorovis is also frequently called “monstrous sheep” or “Prodigious/Monstrous Ovis”, although it wasn’t a sheep at all. The extinct genus of African wild cattle was a gigantic artiodactyl (even-toed ungulate). Pelorovis is related to the modern African buffalo, but a great deal larger and had much longer horns. Each of the two horns could measure almost 200 cm long, to the curve. They pointed away from the head, in a semicircle.

Other

Glyptodonts

• Scientific name: Glyptodontidae
• Diet: Herbivore
• Where: South America
• When: Miocene until the Late Pleistocene

The Glyptodont was one of the most peculiar creatures of the ancient world. The name Glyptodont means “carved tooth” or “grooved tooth”. The animal was related to the modern armadillos, anteaters and sloths. They look a lot like armadillos, but a lot larger. It was about the size and weight of a car, mostly due to the stiff, hard shell, which could be up to 5 cm thick. The Shell consisted of interlocking segments of bone. It had tiny holes which made it possible for hairs and sweat glands to pass in order to regulate its body temperature. The only  vulnerable place of the animal, was the soft belly, but this was hard to expose, because of its size and weight. Unlike a turtle, the Glyptodont could not pull its head back into the shell, to protect itself. It did have boney structures on the head, which made it impossible to bite through. The animal had small legs and could not run at all. It moved at a speed of around 1-3 km an hour.

Ground Sloths (Acratocnus, Catonyx, Eremotherium, Glossotherium, Lestodon, Megalocnus, Megalonyx, Megatherium, Nothrotheriops, Paramylodon, Mylodon)

Cave Bear

• Scientific name: Ursus spelaeus
• Diet: Carnivore
• Where: Europe
• When: Middle and Late Pleistocene

The Cave bear was a species of bears that lived throughout Europe. The animal even reached as far as Iran, but did not live as far as Scandinavia, Northern Britain, or the Baltic countries. Most of its fossils were found in caves, which resulted in both its names: Cave bear and Ursus spelaeus. Cave bears used caves for many purposes: they hibernated there in winter, gave birth to the young ones and sometimes died in caves, mostly during hibernation. The large mammal is a close relative of the modern brown bear, both evolved from a common ancestor, the Ursus arctos, in the Middle Pleistocene. Male cave bears could reach a height of 3,5 metres, while standing on its hind legs, and a weight of around 450 kg, which is three times the weight of an ordinary European bear. Another difference between these two was its anatomy: the cave bear had a less pronounced snout and a lower forehead. Furthermore, his front legs were longer and stronger than its hind legs. It is believed that the cave bears’ extinction was set into motion by competition for food with other animal and competition for shelter by a simultaneous existence with the brown bear. Evidence found in several caves indicate that hominans either worshipped the animal, or used its remains in certain rituals.

Ursus maritimus tyrannus

• Scientific name: Ursus maritimus tyrannus
• Diet: Carnivore
• Where: The Arctic and contemporary Northern Europe
• When: Late Pleistocene

The Ursus maritimus tyrannus was an extinct species of polar bear. The translation of the Latin name means “Tyrant sea bear”. Its appearance must have been very similar to the cave bear, although having slightly longer fur, a bigger jaw line and bigger feet. The bear would have been over 1.80 metres at the shoulders, 3.7 metres long, and about 4 metres high, standing on its hind legs and with an average weight around 1000 kg or more. It is believed that he Ursus maritimus tyrannus was the first white mutation/evolution of the brown bear, halfway through the late Pleistocene between 100,000 and 250,000 years ago.

Horned Gopher

• Scientific name: Ceratogaulus
• Diet: Herbivore
• Where: Woodlands and plains of North America
• When: Late Miocene until Early Pleistocene

The name “Ceratogaulus” is Greek for “horned marten”. It was a member of the extinct fossorial rodent family Mylagaulidae. The animal was about 30 cm long and supported two sharp horns on its snout. It was the smallest mammal ever known to have had horns and the only known horned rodent species (besides the prehistoric armadillo Peltephilus). Their horns were most likely used for digging, or possibly combat. In addition, the animal had small eyes and mole-like, long clawed front hands, supposedly to dig. To avoid the heat and evade predators, the horned gopher buried himself into the ground. The reason why this particular animal had horns is still a big mystery. It is believed by some, that the horns were used for digging as well, but this is highly improbable, considering its positions on the head. Both male and female had a pair of horns of equal size, so this means that they were not used in sexual selection. This leads to the only logical conclusion that the horns were used in order to intimate predators.

Gigantopithecus

• Scientific name: Gigantopithecus
• Diet: Herbivore
• Where: China and Southeast Asia
• When: Pleistocene

The Gigantopithecus is an extinct genus of ape and was the largest primate to have ever walked the earth. It lived around the same time and geographical location as several hominan species. The large mammal could reach a height of 3 metres and weighed between 150 and 230 kg. Its diet consisted mostly of bamboo leaves from the bamboo forests which could be found in contemporary Vietnam, India and China. Because of its enormous size, the Gigantopithecus was not able to climb into trees. His size did have an advantage though; none of the predators was big enough to kill him. Relying on its size, the Gigantopithecus was more similar to gorilla, but in fact it resembled the orang-utan more. It is believed by most experts that the mammal walked on all four legs, because of its weight, like modern gorillas and chimpanzees. There is a minority, however, who believe that the animal moved on two legs only. This is based on the very few jawbone fossils found, all of which are U-shaped and widen towards the rear. This gives room for the windpipe to be within the jaw, allowing the skull to sit straight upon a fully stretched spine like modern humans, rather than roughly in front of it, like the other great apes.

Giant Beaver

• Scientific name: Castoroides
• Diet: Herbivore
• Where: North America
• When: Pleistocene

The giant beaver, as his name suggests, was the largest rodent in North America during the last glacial. It was about 250 cm long and is weighed 60 to 100 kg. Although it might have looked like the modern beaver, it was not closely related. The skull was large and the rodent incisors strongly developed. There are two known species: Castoroides leiseyorum and Castoroides ohioensis. The Castoroides leiseyorum was found in Florida only. It had a length of around 250 cm and an estimated weight of 60-100 kg. It was named after the famous Leisey Shell Pit deposit in Florida, in which it was discovered. These remains are the oldest beaver fossils. The Castoroides ohioensis was in size and weight similar to the Castoroides leiseyorum. The most importance difference is that this specific beaver was younger and so are its fossils. They concentrated around the Midwest of the United States in states near the Great Lakes, particularly Illinois and Indiana, but fossils have also been found in Alaska and Canada to Florida.

Blunt-snouted Dolphin

• Scientific name: Platalearostrum hoekmani
• Diet: Carnivore
• Where: North Sea
• When: Early and Middle Pleistocene

An adult Blunt-snouted dolphin must have been between 4 and 6 meters long and must have had an unique spoon-shaped snout. Compared to modern and other extinct dolphins, the Blunt-snouted dolphin had an extremely short snout, of which the upper jaws (premaxillae), both left and right, pointed outwards. This created the unique spoon-shaped skull and balloon-shaped head. This shape suggests that the animal already disposed of an advanced type of echolocation. Its scientific name was distracted from Latin (platalea = spoon and rostrum = snout) and from Albert Hoekman, a Dutch fisherman who discovered the first part of a Blunt-snouted dolphin skull.

Thylacosmilus

• Scientific name: Thylacosmilus
• Diet: Carnivore
• Where: South America, mainly Argentina
• When: Late Miocene until the Early Pleistocene

The Thylacosmilus was a typical case of convergent evolution: two completely different animals have the same adaptations. The animal had enormous saber-teeth, but was in fact not a saber-toothed cat. The Thylacosmilus was a sparassodonta, closely related to the marsupials. It had long, saber-like upper canines and short, blunt, peg-like lower canines. The canines were located in two mouth guards on the lower jaw, which looked like sheaths. The mouth could be dilated very widely and large muscles were attached to the lower jaw. The teeth show that the Thylacosmilus was a carnivore. Prey was killed with the canines and chewed with the molars. Its estimated weight was around 150 kg, and its size was similar to the Marsupial lion. The Thylacosmilus became extinct during the Great American Interchange when many animals migrated from North America, via Middle America, to South America and vice versa. This became possible due to the fact that the volcanic Isthmus of Panama rose up from the sea floor and bridged the formerly separated continents. The competition became too strong for the Thylacosmilus and it died out.