The animals alive today are only a small fraction of the ones that have once lived.
However, some prehistoric creatures have managed to defy the odds, with many still roaming the planets today.
A lot of them have also managed to retain their appearance, habitat, and unique adaptations, changing very little over the course of geologic history.
Scientists fondly refer to them as “living fossils” because they provide a glimpse into the distant past and the astonishing resilience of Earth’s biodiversity.
In this article, we’ll explore 15 of these prehistoric animals that have persisted in the modern world for several million years.
15. Komodo Dragon
|Scientific Name||Varanus komodoensis|
|Classification||Reptilia, Squamata, Varanidae|
|Length||2.59 meters (8.5 feet)|
|Weight||70 kilograms (150 pounds)|
The Komodo dragon is a large monitor lizard native to the Indonesian islands.
They’re considered the largest and heaviest living lizards in the world, with an average weight of about 154 pounds (70 kilograms).
This is about the same weight as an average human.
Although they’re now endemic to the Islands of Komodo, Flores, Rinca, and Gili Motang in Indonesia, Komodo dragons evolved elsewhere in Asia about 40 million years ago before migrating to Australia.
They moved to Indonesia about 15 million years ago after the landmasses of Australia and southeast Asia collided.
Komodo dragons have been known to eat almost any kind of meat and may sometimes scavenge on carcasses, too.
|Name||Echidna or spiny anteater|
|Classification||Mammalia, Monotremata, Tachyglossidae|
|Length||35–52 centimeters (14-20 inches)|
|Weight||6 kilograms (13 pounds)|
|Location||New Guinea, Australia|
An echidna is a medium-sized mammal that looks like a cross between a badger, an anteater, and a porcupine.
It is also commonly referred to as the spiny anteater because they have a long beak similar to that of anteaters with spines like that of the porcupine.
There are only four living echidna species, and they’re all native to Australia, Tasmania, and New Guinea.
Although they’re mammals, echidnas are unique because they reproduce by laying eggs instead of giving birth to live young.
Echidna and the platypus are the only mammals known to exhibit this behavior.
Experts think the echidna may have evolved about 50 million years ago from platypus-like mammals.
|Classification||Aves, Casuariiformes, Casuariidae|
|Length||1– 1.7 meters (3.2–5.5 feet)|
|Weight||72 kilograms (160 pounds)|
|Location||Australia and New Guinea|
Birds are the closest living animals to the dinosaurs, and the cassowary is one of the best examples of this.
It belongs to a family of birds known as the ratites that evolved about 60 million years ago.
The cassowary shares many similarities with the dinosaurs, such as its three-toed feet with sharp dagger-like talons that can inflict serious injuries.
Each claw can be as long as 125 millimeters (5 inches).
The cassowary is generally shy but has been labeled as the world’s most dangerous bird because of its tendency to attack and inflict potentially fatal injuries when disturbed.
|Scientific Name||Gavialis gangeticus|
|Classification||Reptilia, Crocodilia, Gavialidae|
|Length||3–6 meters (9.84–19.69 feet)|
|Weight||160–600 kilograms (350–1,300 pounds)|
The gharial (Gavialis gangeticus) is a crocodilian species native to India and Nepal.
Also known as the fish-eating crocodile, the gharial is known for its long, slender snout adapted for hunting fish underwater.
The status of the gharial as a living fossil is sort of controversial.
Fossils of ancient gharial-like crocodilians have been found in rocks dating back to over 70 million years ago.
However, genetic evidence suggests a younger age for this crocodilian (as recent as 30 million years ago).
However, the fact that the gharial has not changed much since their early days of the Cretaceous means they qualify to be regarded as prehistoric species.
|Scientific Name||Atopogale cubana|
|Classification||Mammalia, Eulipotyphla, Solenodontidae|
|Length||28–32 centimeters (11–13 inches)|
|Weight||0.7–1.0 kilograms (1.5–2.2 pounds)|
|Location||Cuba, Haiti, and Dominican Republic (Caribbean)|
The solenodon is a rare and reclusive mammal that is only found in the Caribbean (Cuba, Haiti, and the Dominican Republic).
It is a primitive creature that has been around since the Late Cretaceous Period and has remained unchanged for up to 76 million years.
The solenodon is one of the few venomous mammals on Earth.
The toxic venom of this tiny mammal is similar to the neurotoxic venom of many modern snake species.
Although an omnivore, the solenodon’s diet consists mainly of insects, worms, and other invertebrates.
This shrew-like mammal may scavenge on carrion from various animals.
It is capable of hunting small vertebrate prey, including reptiles and amphibians.
10. Frilled Shark
|Scientific Name||Chlamydoselachus anguineus|
|Classification||Chondrichthyes, Hexanchiformes, Chlamydoselachidae|
|Length||2.0 meters (6.6 feet)|
|Weight||91–136 kilograms (200–300 pounds)|
|Location||Deep waters of the Atlantic and Pacific Ocean|
Sharks, in general, have been around for several million years, but one of the most primitive of them still living today is the frilled shark—Chlamydoselachus anguineus.
This deep-sea inhabitant is known for its primitive eel-like body, unlike many more modern shark species.
The shark’s name refers to the fringed appearance of the shark’s gill slits.
The frilled shark evolved more than 80 million years ago, which is why it is considered a living fossil today.
It is found in deep waters of the Atlantic and Pacific oceans at depths of more than 1,000 meters.
This living relic can grow to a length of more than 6.6 feet and preys on cephalopods such as squids, bony fish, and smaller sharks.
9. Chinese Giant Salamander
|Name||Chinese Giant Salamander|
|Scientific Name||Andrias davidianus|
|Classification||Amphibia, Urodella, Cryptobranchidae|
|Length||1.15 meters (3.8 feet) in length|
|Weight||25–30 kilograms (55–66 pounds)|
The Chinese giant salamander (Andrias davidianus) is the largest salamander species in the world and is also one of the biggest amphibians around.
It is endemic to central China, where it is present in the wild and also kept as pets or reared on farms.
Andrias belongs to the family Cryptobranchidae, a family of aquatic salamanders that evolved about 170 million years ago.
The Chinese giant salamander is a carnivore that preys on a wide range of animals, including insects, worms, crustaceans, fish, and other amphibians.
It has also been known to exhibit cannibalism, preying on smaller members of its species.
|Classification||Reptilia, Crocodilia, Crocodylomorpha|
|Length||up to 7 meters (23 feet)|
|Weight||2,000 kilograms (4,400 pounds)|
|Location||Africa, Asia, Australia, Americas|
The crocodilians share a common ancestry with the dinosaurs, appearing as far back as the Triassic Period, about 250 million years ago.
But the Crocodilia group, which includes living species of true crocodiles, alligators, and caimans, evolved during the Cretaceous Period, about 95 million years ago.
This means they were around during the extinction event that wiped out the dinosaurs 66 million years ago and somehow managed to survive.
Crocodiles have remained virtually the same morphologically since they first evolved, although some extinct species, such as the Deinosuchus, were considerably larger than present-day forms.
The true crocodiles separated from the main crocodilian lineage about 55 million years ago, during the Eocene epoch.
They’re apex predators found in various parts of the world, including Africa, Asia, the Americas, and Australia.
|Scientific Name||Sphenodon punctatus|
|Classification||Reptilia, Rhynchocephalia, Sphenodontidae|
|Length||80 cm (31 in)|
|Weight||1.3 kg (2.9 lb)|
The tuatara (Sphenodon punctatus) is a reptile native to New Zealand.
In fact, it is the largest reptile in New Zealand, with an average length of about 61 centimeters (24 inches) for adult males.
Tuatara belongs to an ancient lineage of reptiles whose origin dates back to the Triassic Period (about 250 million years ago).
This reptile is the only living representative of the order Rhynchocephalia.
All other members of this order went extinct about 60 million years ago.
Although they resemble modern lizards and are distantly related to them, tuataras are unique in their own right.
They have distinctive features, such as a spiny crest along their back, which is more pronounced in males than in females.
Tuatara are currently endangered in New Zealand, with a population that is mainly restricted to 32 offshore islands.
6. Alligator Snapping Turtle
|Name||Alligator snapping turtle|
|Scientific Name||Macrochelys temminckii|
|Classification||Reptilia, Testudines, Chelydridae|
|Length||29 inches (73.7 centimeters)|
|Weight||155 –175 pounds (70–80 kilograms).|
The alligator snapping turtle is popular for its primitive look.
It is often described as having a dinosaur-like appearance, which isn’t out of place since it evolved alongside these prehistoric reptiles.
The name of this turtle is a reference to its powerful jaws and distinct spikes on its shells, similar to the ridged skin of alligators.
Modern snapping turtles are quite similar in appearance to their prehistoric ancestors that emerged more than 215 million years ago.
The family, which includes modern snapping turtles (family Chelydridae), evolved in North America and has remained relatively unchanged for up to 90 million years.
The alligator snapping turtle (Macrochelys temminckii) is the largest of all the freshwater turtle species.
It has an interesting way of catching prey, which involves laying still in the water while wagging its brightly-colored, worm-like tongue.
The turtle then snaps its jaws shut to catch any curious fish that swims too close to investigate.
5. Mantis Shrimp
|Classification||Malacostraca, Hoplocarida, Stomatopoda|
|Length||10–38 centimeters (3.9–15 inches)|
|Weight||12-90 grams (0.4–3.2 oz)|
Despite the name, mantis shrimps are not actually shrimps.
They belong to the order Stomatopoda, which means they’re better described as shrimp-like crustaceans.
The order Stomatopoda has existed for more than 400 million years.
The suborder that gave rise to the current living species of mantis shrimp evolved about 193 million years ago.
The mantis shrimp is known for its incredible color vision and its formidable striking abilities, which it uses to catch prey and defend itself against predators.
Mantis shrimps are active predators capable of hunting, chasing, and killing prey—a rare habit for a crustacean.
Some species have limbs modified into specialized clubs for striking at prey, while others have sharp forelimbs that they use like a spear for seizing prey.
4. Tadpole Shrimp
|Classification||Branchiopoda, Notostraca, Triopsidae|
|Length||11 centimeters (4.5 inches)|
|Weight||70 kilograms (150 pounds)|
The Triops, or tadpole shrimp, is a tiny crustacean that can be found in freshwater lakes and ponds all over the world.
It belongs to the order Notostraca, along with the similar-looking members of the Lepidurus genus,
The tadpole shrimp are known for their tadpole-like form characterized by a long, segmented body and a pair of antennae on their tail end.
The order Notostraca has been around since the Devonian about 360 million years ago.
The two living genera split from the main lineage during the Triassic or Jurassic Period, between 152.3 and 233.5 million years ago.
Tadpole shrimps are filter feeders and are an important part of the aquatic food chain.
They can feed on almost anything and are often used to control pest populations and get rid of mosquito larvae.
3. Chambered Nautilus
|Scientific Name||Nautilus pompilius|
|Classification||Cephalopoda, Nautilida, Nautilidae|
|Length||20 centimeters (8 inches)|
|Weight||1.27 kilograms (2.8 pounds)|
|Location||Oceans in the Indo-Pacific region|
The chambered nautilus is the best-known of the nine nautilus species that are still living today.
It is also commonly referred to as the pearly nautilus.
The origin of the nautilus order (order Nautilida) can be traced back to about 500 million years ago.
This makes them the most primitive cephalopods (predating squids and octopuses).
The Nautilus genus and their closely related Allonautilus genus are the only living representatives of this previously large and diverse order.
The chambered nautilus is both a carnivore and a scavenger.
It preys on shellfish and crabs but also feeds on carrion and detritus that fall to the bottom of the sea from the surface.
2. Horseshoe Crab
|Scientific Name||Limulus polyphemus|
|Classification||Chelicerata, Xiphosura, Limulidae|
|Length||60 centimeters (24 inches)|
|Weight||4 kilograms (9 pounds)|
|Location||North America and Asia|
The horseshoe crab (Limulus polyphemus) is an arthropod whose evolution dates back more than 450 million years ago.
Despite the name and superficial resemblance, the horseshoe crab is unrelated to crabs or other crustaceans.
Instead, it is more closely related to spiders, ticks, and scorpions.
Horseshoe crabs have been around since the Ordovician Period and can still be found in the shallow waters along the Atlantic coast of North America.
It is consumed as a delicacy in some parts of Asia but is more popular today for its role in biomedical research.
The horseshoe crab’s blue blood is useful for detecting bacterial endotoxins in the human body.
They are bottom-dwelling carnivores and feed on a wide range of prey, including worms, mollusks, crustaceans, and small fish.
|Classification||Sarcopterygii, Actinistia, Coelacanthiformes|
|Length||2 m (6.5 ft)|
|Weight||80 kg (176 lb)|
|Location||South Africa, Indonesia. (Africa and Asia)|
This is a group of lobe-finned fish that evolved about 400 million years ago.
However, only two species (West Indian Ocean coelacanth and Indonesian coelacanth) are currently alive.
The entire group was thought to have gone extinct about 66 million years ago during the Cretaceous Period.
This was until a coelacanth was rediscovered off the coast of South Africa in 1938.
Coelacanths are more closely related to the lungfish and tetrapods than they are to the ray-finned fishes.
Their existence today is very important because they provide valuable insights into the evolution of land animals.
Coelacanths are renowned for their ability to live very long.
Their estimated lifetime is similar to that of humans.
But they do have a long gestation, which can last for as long as five years.