Before man became a hunter and made his way to the top of the food chain, the Felidae, or cats, were the most successful, powerful predators in most of the world. Even today, big cats such as tigers, lions, jaguars and leopards keep causing admiration and fear, but these magnificent beasts are dwarfed by some of their extinct relatives.

The Giant Cheetah (Acinonyx pardinensis), belonged to the same genus as our modern day Cheetah (Acinonyx jubatus), and probably looked very similar, but it was much bigger.
At around 120-150 kgs (265-331lbs), it was as large as an African lioness, and was able to take on larger prey than its delicate modern day counterpart.
The Giant Cheetah was also adapted to fast running, but there’s some debate on whether it could run as fast as the modern Cheetah, due to its larger weight, which, according to some, probably made it somewhat slower.
Others, however, have suggested that the Giant Cheetah, having longer legs and bigger heart and lungs, was probably able to run as fast, or even faster, than the cheetah does today – that’s over 115 kph (72mph)! The Giant Cheetah lived in Europe and Asia (from Germany and France to India and China) during the Pliocene and Pleistocene epochs; it went extinct during the last Ice Age. Due to its living in colder environments than modern day Cheetahs, it is possible that the Giant Cheetah had longer fur and perhaps a lighter coloration.

Xenosmilus is a relative to Smilodon (the ever famous “sabertoothed tiger”), but instead of having long, blade-like fangs, it had shorter and thicker teeth. All of its teeth (not only the canines) had serrated edges to cut through flesh, and were more like the teeth of a shark or a carnivorous dinosaur, than the teeth of modern day cats.
Xenosmilus didn’t strangle its prey as modern day cats do; it only had to bite off a huge chunk of flesh from its victim, and wait until it bled to death. A Xenosmilus’ kill was much bloodier and messier than that of any big cat today!
Xenosmilus was a very big cat for today’s standards; at 180-230 kgs (397-507lbs), it was as big as most adult male lions and tigers, and was much more robust, with shorter, stronger limbs and a very powerful neck. The remains of this cat have been found in Florida, along with those of giant prehistoric peccaries (pig-like animals) which were seemingly its favorite meal. It lived during the Pleistocene period but no one knows exactly when it went extinct; whether it encountered (or ate) humans or not is anyone’s guess.

Jaguars today are rather smallish cats if compared to lions or tigers; they usually average 60-100 kgs (132-220lbs), and the largest males (recorded from South America) were around 150 kgs (330lbs), about the size of an African lioness. In prehistoric times, however, both North and South America were home to gigantic jaguars, belonging to the same species as modern day jags (Panthera onca) but much bigger.
These giant jaguars also had longer limbs and tails than jaguars living today; scientists believe that jaguars used to be open plain denizens, but that competition with American lions and other big cats forced them to adapt to more forested environments, where they developed their modern short-legged appearance.
Giant prehistoric jaguars were about the size of a fully grown lion or tiger, and were probably several times stronger, with a much stronger bite.
There are two subspecies of prehistoric giant jaguars known to date; Panthera onca augusta, from North America, and Panthera onca messembrina, from South America (also known as the Patagonian panther). Both of them were active during the Pleistocene period, but went extinct about 11.000 years ago, during the last Ice Age.

Unlike the Giant Jaguar mentioned before, the European jaguar or Panthera gombaszoegensis did not belong to the same species as modern day jags. Nobody knows what the European Jaguar looked like; some scientists have suggested that it probably looked much like a modern day jaguar (hence the name), or perhaps, a cross between a lion and a jaguar. A fossil feline from Eastern Africa has been said to resemble the European jaguar, and described as having “tiger-like” features as well.
Regardless of its external appearance, it is obvious that it was a huge predator, weighing up to 210 kgs (463) or more, and probably at the top of the food chain in Europe, 1.5 million years ago. Its fossil remains have been found in Germany, France, England, Spain and the Netherlands.

The Cave lion was a gigantic subspecies of lion, weighing up to 300 kgs (661lbs) or more (and therefore, being as large as the Amur or Siberian tiger, the largest cat of our days).
It was one of the most dangerous and powerful predators during the last Ice Age in Europe, and there is evidence that it was feared, and perhaps worshiped, by prehistoric humans. Plenty of cave paintings and a few statuettes have been found depicting the Cave Lion. Interestingly, these show the animal as having no mane; barely a ruff around the neck sometimes, as in modern day tigers.
Confusingly, some cave paintings also show the Cave Lion as having faint stripes on its legs and tail. This has led some scientists to suggest that perhaps the Cave Lion was actually more related to the Tiger. Genetic studies on the ancient bones, however, have confirmed the original idea that the Cave Lion is, indeed, a lion after all – albeit, if cave artists are to be trusted, a very unusual looking one.

Also known as the “Scimitar cat”, Homotherium was one of the most successful felines in prehistoric times, being found in North and South America, Europe, Asia and Africa. It adapted well to a variety of habitats, including the sub-arctic tundra and survived for five million years until its extinction 10,000 years ago.
Homotherium was seemingly a pack hunter, adapted to fast running and active mostly during day (thus avoiding competition with other, nocturnal predators). It had very long forelegs and shorter hind legs, which gave it a slightly hyena-like appearance. Although Homotherium is not very famous for its size, some fossil remains of a Scimitar cat unearthed recently in the North Sea suggest that they could reach 400 kgs (882lbs) in weight, being larger than modern day Siberian tigers.
If you are wondering what these enormous, pack-hunting cats ate, some paleontologists believe that they were quite skilled mammoth hunters, although their ability to run at high speed would allow them to chase after fleet-footed animals as well.

Despite Smilodon’s fame as the classic “sabertooth tiger”, its short tail and different body proportions were very different from an actual tiger.
Machairodus, on the other hand, probably looked pretty much like a gigantic tiger with saberteeth; it had very tiger-like proportions and a long tail, although it is impossible to know if it had stripes, spots or any other kind of fur markings.
Machairodus is seldom mentioned as a giant feline, but some fossil remains found in Chad, Africa, (and classified as a new species, Machairodus kabir), suggest that this creature was among the largest cats of all times- weighing up to 490 (1080lbs) or perhaps 500 kgs (1102lbs), and being “the size of a horse”. It fed on elephants, rhinos and other large herbivores which were abundant at the time.
Machairodus kabir probably looked somewhat like the gigantic “sabertooth tiger” in the film 10.000 B.C, although sadly, it went extinct during the Miocene period, long before the appearance of humans.

Often called the largest cat of all times, the American lion or Panthera atrox, is probably the best known of all prehistoric cats after Smilodon.
It lived in both North and South America (from Alaska to Peru) during the Pleistocene epoch, and went extinct 11,000 years ago, at the end of the last Ice Age. Most scientists believe that the American Lion was a gigantic relative to modern lions, perhaps even belonging to the same species (in which case the correct name would be Panthera leo atrox).
However, others are not so sure, and suggest that the American lion, although closely related to the lion, was a separate species and probably looked quite different on the outside. Recently, it was suggested that the American lion was probably more similar to the jaguar.
One thing is certain; the American lion was the largest cat in North America during the Ice Age, weighing up to 470 (1036lbs), perhaps even 500 kgs (1102lbs), and being able to take on very large prey. There is still some debate about its hunting technique, for although modern day lions hunt in groups, American lion remains are scarce, suggesting that these cats were probably solitary hunters.
This would make sense if we consider that the North American Smilodon fatalis, a species of sabertooth, was seemingly a pack hunter. By hunting alone and preying on different animals, it may be that the American lion avoided competition with the sabertooth, explaining why both cats coexisted successfully for such a long time.

This is easily the most obscure cat in the list, being known from fragmentary remains which have yet to be formally described. I should mention that the “Pleistocene tiger” is not a separate species, but rather the “early version” of the same tigers we see today. Tigers evolved somewhere in Asia about 2 million years ago, specifically to prey on the enormous diversity of large herbivores living on the continent at the time. Tigers are the largest felines nowadays, with large Bengal and Siberian males reaching up to 300 kgs (661lbs) or more.
However, during the Pleistocene, the food supply was greater, and so the tigers themselves were bigger. Some fragmentary remains (including massive jaws and fangs) have been found in Russia, China and Java, suggesting that these “Cave tigers” could reach up to 490 kgs (1080lbs) in weight, being worthy contenders for the title of largest cat ever.

The ever popular “sabertooth tiger”, Smilodon is one of the most famous prehistoric predators, and also one of the most formidable.
There were at least three species living in both North and South America; the smallest species, Smilodon gracilis, was about the size of a modern day jaguar, while Smilodon fatalis was as big as a lion.
However, the South American species Smilodon populator dwarfed both of them, weighing 300 kgs (661lbs) on average and reaching up to 500 kgs (1102lbs) when fully grown!
Smilodon was not as agile as modern day big cats, but it was immensely powerful, with thicker, stronger limbs and neck than modern day cats, and particularly long claws to hold on to prey. Its fangs could reach 30 cms (12″) in length, and were perfect for causing mortal injury to mammoths, ground sloths and possibly any large animal unlucky enough to be ambushed by this super predator.
Smilodon went extinct 10,000 years ago, meaning it encountered humans, and probably hunted them once in a while. But perhaps the most amazing thing about Smilodon, is that it is the only prehistoric cat known to have caused the extinction of an entire species. The victim was another formidable predator, the saber-toothed marsupial or marsupial relative known as Thylacosmilus.
This beast ruled South America for millions of years, until the sea levels became lower and North America became connected to South America.

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Who hasn’t heard of a tyrannosaurus Rex or a velociraptor thanks to movies like Jurassic Park? When we think of dinosaurs, we almost all think of a very small subset of these giant creatures from history. But perhaps more interesting are those which are far less familiar to us all. This list is just a small selection of monstrous or weird-looking creatures from ancient times, most of which are little known to the public.


This is a fairly well known prehistoric monster, but it is just so big and scary that it deserves to be in this list. Megalodon (technically called a Carcharocles megalodon) was a gigantic shark, closely related to today’s makos and great whites. It could grow up to 20 meters long and weigh up to 60 tons, being almost six times larger than Tyrannosaurus rex! Obviously, the only thing in the sea big enough to feed Megalodon where whales, and indeed, the giant shark’s bite marks have been found in the fossil remains of whales all around the world. Although many people like to imagine encounters between Megalodon and T-Rex, or dinosaur-like marine reptiles, the truth is Megalodon appeared long after the extinction of such creatures, and it wasn’t seen alive by any humans either, although it was still roaming the oceans when our australopithecine relatives took their first steps out of the jungle.

Since the formidable Smilodon (better known as saber-toothed tiger) is too well known, we have decided to go for a refreshing change. Enter Xenosmilus, possibly the nastiest feline ever to have existed. The remains of this very large cat (the size of a lion or tiger, but more robust) were recently found in Florida along with the remains of many unlucky giant peccaries (similar to wild pigs) that fell prey to it. Instead of strangling prey or breaking their neck as lions do, or stabbing them as the sabertoothed tiger did, Xenosmilus acted more like a shark or a carnivorous dinosaur, biting off a huge chunk of flesh and causing massive blood loss and shock in a matter of seconds. Compared to modern day felids, a Xenosmilus’ kill would probably be extremely bloody; so much in fact that it would probably not be shown in Animal Planet! Since we don’t know when exactly Xenosmilus became extinct, we can’t tell if humans ever met this cat, or fell prey to it.

Pulmonoscorpius
This is by far the smallest creature of the list, but it would still cause hysteria, and perhaps even some heart attacks, if it showed up today. It was very similar to today’s scorpions but could grow up to one meter long, perhaps more, and was armed with sharp chelae (claws) and a venomous stinger. Of course, we don’t know how toxic its venom was, but considering the considerable amount it injected with each attack, it was most likely a very deadly critter indeed. A predator, Pulmonoscorpius roamed the swampy forests of the Carboniferous in what is today Scotland. Just so you know, during the Carboniferous there were also giant roaches the size of house cats, dragonflies the size of hawks, and centipede-relatives up to three meters long. No kidding.

Azhdarchids were a kind of pterosaur (most popularly known as pterodactyls) which included the largest flying creatures ever to have existed. Some of them had wingspans of 12 to 15 meters, making them as large as a small plane (although they were obviously not as heavy). But what makes Azhdarchids really strange are their body proportions; they had ridiculously long legs, necks and beaks, and very small bodies, as well as relatively short wings. Scientists believe that they did not hunt on the wing, but rather walked on the ground hunting for any animal they could catch and swallow whole- that included dog-sized, perhaps even man-sized creatures! Standing on all fours, the largest Azhdarchids were as tall as a modern day giraffe… and almost as tall as a T-Rex.

Madtsoia
Madtsoia would be the worst nightmare of anyone with a phobia of snakes. Although only fragmentary remains are known, it is claimed to have reached the immense length of 15-20 meters! This creature appeared in the Cretaceous period and possibly dined on dinosaurs. It was similar to today’s boas and pythons in that it was not venomous, but rather squeezed its victims to death using its immense muscular strength. Madtsoia was such a successful predator, that it managed to survive the extinction that wiped out dinosaurs and other animals, but it finally went extinct about 45 million years ago. Other giant snakes are known to have existed, including one that was said to reach 29 meters in length!

Terror birds, formally known as Phorusrhacids, were the top predators in South America and parts of North America during the Miocene, Pliocene and Early Pleistocene periods, before they were replaced by big cats and other carnivorous mammals. They were unable to fly, but could run very fast (as fast as a cheetah, according to some scientists!) and were very large; the largest species could grow up to three meters tall and weigh up to half a ton. Their main weapon was their head, which could be up to one meter long, allowing them to swallow prey as large as a dog in one single gulp! However, thanks to the hooked tip of the bill, similar to that of eagles and hawks, the terrors birds could kill and devour prey much larger than a dog, including horses, camels, etc.

Epicyon
Epicyon could well be described as a giant pitbull on steroids. It was a member of the Canidae or dog family, but whereas modern day canids are built for speed and endurance, Epicyon was built for brute strength, and had jaws so powerful that they could crush bone as if they were crackers! This beast ruled the plains of North America for fifteen million years, before it was replaced by big cats (including sabertooths).

This list looks at fish that were around in remote, prehistoric times and have survived to our time, still keeping their “prehistoric” looks to prove it. Feel free to mention those I have excluded in the comments.

Hagfish

According to the fossil record, hagfish have existed for over 300 million years, which means they were already old when dinosaurs took over the world! Found in relatively deep waters, these animals are sometimes called slime eels, but they are not really eels, and actually, they may not even be fish at all, according to some scientists. They are very bizarre animals in all regards; they have a skull but lack a spine, and they have two brains. Almost blind, they feed at night on the carcasses of large animals (fish, cetaceans etc) which fall to the sea bottom. They owe their “slime eel” nickname to the fact that they produce a slimey substance to damage the gills of predatory fish; as a result, they have virtually no natural enemies.

Lancetfish

The lancetfish has a very obvious “prehistoric” appearance, with those fierce-looking, sharp teeth on its jaws and the sail on its back, reminiscent of that of some dinosaurs (although, in the lancetfish the sail is actually an enlarged dorsal fin). Even its scientific name has a dinosaurian sound to it (Alepisaurus ferox). Up to two meters (6′ 6″) in length, this predator is found in all the oceans except for polar regions; very voracious, it feeds on smaller fish and squid, and has known to feed on members of its own species sometimes.

Arowana

Belonging to the ancient group of the Osteoglossids, these fish already existed in the Jurassic period. Today, they are found in the Amazon, and in parts of Africa, Asia and Australia. Sometimes kept as exotic pets, arowanas are voracious predators that feed on any small animal they can catch, including birds and bats which they catch in mid flight (they are able to leap up to 2 meters (6′ 6″) into the air). In China, arowanas are known as “dragon-fish” due to their appearance, and they are thought to be harbingers of good luck.

This deep sea predator, one of the most primitive sharks alive today, is a relic from the Cretaceous period, when dinosaurs ruled the Earth. Seldom seen alive, and only recently filmed for the first time, the frilled shark can grow up to 2 meters (6′ 6″) (with females being larger than males) and they live in deep waters, where they feed mostly on squid. They are not dangerous to humans, and as a matter of fact, most frilled sharks spend their whole lives without seeing a human being. Only dead or dying specimens are usually seen and recorded by fishermen or scientists.

Sturgeon

Another survivor from the age of dinosaurs (they were already around in the early Jurassic), the sturgeon is well known for being one of the main sources of caviar (which is made out of their roe or egg masses); due to overfishing, these magnificent, armored fish are sadly endangered nowadays. The largest sturgeon species can grow up to 6 meters (19′ 7″) long, being as large as most great white sharks; they feed on small animals from the sea bottom and pose no danger to humans, unless provoked (although they are so big that they have hurt, and even killed, people unintentionally by leaping out of the water and landing on boats!)

Arapaima

A close relative to the arowana (see #8), the Amazonian arapaima is sometimes considered to be the largest freshwater fish in the world. According to early descriptions, it could grow up to 4.5 meters (14′ 8″) long, but today, enormous individuals like these are seldom found and most adult arapaimas average 2 meters (6′ 6″) long. These slow moving predators feed on smaller fish, crustaceans and whatever small animal they can fit in their mouth. An interesting trait of this fish is that it needs to breath oxygen from the air, like a cetacean, in order to survive. Arapaimas pose no danger to humans and are often hunted for their meat; unfortunately, they are very scarce nowadays. Although the arapaima seemingly appeared in the Miocene period, it belongs to a much older family, the Osteoglossidae, and therefore its origins can be traced back to the age of dinosaurs.

Sawfish

This critically endangered animal is a survivor from the Cretaceous period, and can be found both in saltwater or in rivers and creeks, and has been found up to 100 kms inland. Up to 7 meters (23′) in length, sawfish may look like sharks but are actually more closely related to rays. Their “saw” is both a weapon and a sensory organ, covered on electro-sensitive pores which allow it to sense prey despite its terrible eyesight. Although usually peaceful, the sawfish can become extremely dangerous if provoked. Due to an extraordinary fossil, we know that gigantic, prehistoric sawfish were probably a staple food for the largest carnivorous dinosaur, Spinosaurus, as a vertebra from the fish was found stuck between the dinosaur’s teeth.

Alligator Gar

This formidable, thick scaled predator is found in the southern US and northern and eastern Mexico, being the largest freshwater fish in North America (although it sometimes wanders into the sea). It can grow up to 4 meters (13′) long and weigh up to 200 kgs (440lbs). Gator gars are so called because of their reptilian appearance and long jaws, armed with a double row of sharp teeth. They are voracious ambush predators and have been known to bite humans on occasion, although no confirmed deaths due to alligator gars have been recorded to date. Gars are among the oldest fish alive today; their origins can be traced back to the Cretaceous period.

These african fish are often called “dinosaur eels”, due to their reptilian appearance and serrated dorsal fin, reminiscent of some dinosaurs’ spiked backs. They are not really eels, but members of the bichir family. Bichirs were already around in the Cretaceous, so the “dinosaur” part of their name is actually fitting in a way. Although often sold as exotic pets, dinosaur eels are prone to escaping their fish tanks. They can survive out of the water for long periods of time as long as their skin remains wet, which enables them to wander far away from their tank.

The Coelacanth is the most famous of all “living fossils” and deserves to be #1 in this list, because it is the best example of a “Lazarus taxon”, this is, animals that were supposed to be long extinct and are unexpectedly found to be alive. Coelacanths were supposed to have become extinct in the Cretaceous period, along with the dinosaurs, but in 1938, a live specimen was caught in South Africa. Since then, more specimens have been seen and photographed, and a second coelacanth species was even found in Indonesia in 1999. Coelacanths are large predators, up to 2 meters (6′ 6″) long; they feed on smaller fish, including small sharks, and are usually found in deep, dark waters. Although rarely captured and consumed due to their horrible taste, coelacanths are critically endangered nowadays.