A living fossil is a species that has not changed significantly over millions of years and closely resembles its ancestors found in the fossil record. Charles Darwin coined the term “living fossil” in 1859 to describe living species that still looked like their ancestors millions of years ago and were often the last surviving lineage. Anatomically, these species tend to appear unchanged, although genetically, the species are constantly evolving. Plate tectonic activity has had a profound effect on the rate of evolution of coelacanths throughout their 400-million-year history.
The term “living fossil” is hotly debated among scientists, as the definition of what counts as unchanged and over what periods of time varies widely. But in general, living fossils are ancient species with anatomies that still closely resemble related fossils from earlier in evolutionary history.
Coelacanth (Coelacanthiformes)
The coelacanth is an elusive, deep-sea, ancient bony fish found off the coasts of Africa and Indonesia. Coelacanths first appeared in the fossil record 400 million years ago during the Devonian Period (419.2–358.9 million years ago) and ceased to appear around the time non-avian dinosaurs became extinct. Scientists thought that these endangered creatures had been extinct for more than 65 million years until a coelacanth (Latimeria chalumnae) found in the western Indian Ocean off the coast of South Africa was discovered in 1938. This unexpected appearance led to its being named the Lazarus species.
The coelacanth is known as the Lazarus species because it was thought to have gone extinct 65 million years ago until it was discovered alive in 1938.
Coelacanths can grow up to 6.6 feet (2 meters) long and weigh up to 198 pounds (90 kilograms). And one study found evidence that the creatures can live up to 100 years. Because the primitive species has several fleshy, lobe-shaped fins that resemble limbs, many scientists believe that coelacanths may have played a role in the evolution of fish into land animals.
An ancient coelacanth that has been around for about 419 million years never stopped evolving, despite its reputation as a “living fossil.” A new discovery shows that it evolved faster when plate tectonics was most active.
Ancient fish thought to be “living fossils,” largely unchanged since the time of the dinosaurs, are actually evolving rapidly—and they evolved faster when Earth’s continents were moving faster, according to fossils from a newly identified species of coelacanth.
The findings suggest that large-scale continental migrations may drive the evolution of life, the researchers reported Sept. 12 in the journal Nature Communications.
Coelacanths are large fish that evolved 410 million years ago. Once known only from fossils, they were thought to be extinct until a fisherman in South Africa pulled one out in 1938. Biologists dubbed the modern coelacanth a “living fossil” and believed it had not evolved much over millions of years.
The skull bones of the coelacanth Ngamugawi virngarri after they were acid-etched from a rock at Museum Victoria, 2009. Professor John Long
The two species of coelacanth living today, Latimeria chalumnae and Latimeria menadoensis, are more closely related to other early fishes, such as the lungfishes, than to modern ray-finned fishes.
But now new “bridge” fossils show that coelacanths never stopped changing. The fossils, beautifully preserved in three dimensions, provide one of the best anatomical glimpses yet into the coelacanth’s history. Combined with other coelacanth fossils, the discovery suggests that the more geologically active the environment, the more evolutionary change the fish underwent.
“Ironically, plate tectonic activity has had a strong influence on the pace of coelacanth evolution throughout their 400-million-year history,” said study first author Alice Clement, an evolutionary biologist at Flinders University in Australia.
The newly identified coelacanth, Ngamugawi wirngarri, was discovered in the Kimberley region of northwestern Australia. It’s now tropical, with landscapes ranging from mountains to grasslands. But 385 million years ago, it was a thriving reef, home to at least 50 species of fish. “In a sense, it was Australia’s first great barrier reef, extending hundreds of kilometres from shore,” Clement said.
An artist’s rendering of the Ngamugavi Virngarri coelacanth in its natural habitat. Katrina Kenny
Two specimens of the new coelacanth species were first discovered in 2008. It was the first coelacanth from the site, so researchers knew they had found something special. But it took years to prepare the fossils and analyze the finds.
The scientific name of the newly identified species means “ancient fish” in the language of the indigenous Gunyandi people who live near the fossil beds. The species was small, only about 7.8 inches (20 centimeters) long. Modern species, by contrast, are about 6.5 feet (2 m) long.
The fish’s anatomy fell between the earliest “primitive” species, which date back 410 million years, and species that still swim in the oceans today. By looking at the differences between the fossils over time, the researchers learned that while the fish’s larger features, such as its body shape, had remained unchanged since the Cretaceous period more than 66 million years ago, the bones of the jaw and skull had continued to evolve.
Recent studies suggest that the coelacanth can live up to 100 years. Bruce Henderson
In fact, study co-author Richard Cloutier, an evolutionary biologist at the University of Quebec at Rimouski, told Live Science that if the researchers had had to limit themselves to just the skull, “we would never have thought it was a ‘living fossil’ because it had changed so much.”
The researchers found that this change was linked to faster rates of continental drift, even more than environmental factors such as ocean oxygen levels or water temperature.
“I believe,” Clement said, “that increased plate tectonic activity is creating new habitats or splitting existing populations in half, allowing them to continue their own natural evolutionary experiments.”
Initial studies suggested that coelacanths had a maximum lifespan of 20 years. But this finding was at odds with other aspects of the fish’s life history, including a slow metabolism and low oxygen uptake — traits typically associated with longevity. In 2021, researchers used an advanced aging technique to count calcified structures on coelacanth scales — similar to counting growth rings on a tree — and found that they can live for up to 100 years.
The head of a preserved coelacanth specimen in Beijing, China. Alamy
The study also found that they reach sexual maturity slowly, with males reaching sexual maturity at age 40 and females at age 58. They also have the longest gestation period of any known vertebrate, lasting five years.
And that’s not all. Coelacanths can also hunt while standing on their heads, thanks to their special skeleton, with most of their bone mass concentrated in their head and tail.
In 1997, nearly 60 years after the coelacanth was rediscovered in the western Indian Ocean, scientists discovered another species of coelacanth in Indonesia. Known locally as raja laut (king of the sea), it was given the scientific name L. menadoensis.
Horseshoe crab (Limulidae)
Horseshoe crabs first appeared more than 300 million years ago, making them even older than non-avian dinosaurs. The species has not evolved much in that time. Although horseshoe crabs look a lot like prehistoric crabs, they are more closely related to spiders and scorpions.
Four species of horseshoe crabs—the Atlantic horseshoe crab (Limulus polyphemus), found along the Atlantic coast of North and Central America, and three species—the Indo-Pacific horseshoe crab (Tachypleus gigas), threespine (Tachypleus tridentatus), and mangrove (Carcinoscorpiu rotundicauda), found in coastal waters of Asia—tend to be found in regions where rivers flow into the sea.
Horseshoe crabs have been around for 300 million years. Danielle Duncan
Crabs have a tough exoskeleton, 10 legs for moving along the ocean floor, and one pair of legs, known as chelicerae, for moving food into their mouths. Their blood contains a copper-based protein and turns blue when exposed to oxygen. Crab blood is used in medical research to develop vaccines.
Overfishing and exploitation by the biomedical and bait fishing industries have devastated the horseshoe crab population. Around 700,000 horseshoe crabs are pulled from beaches during spawning season and bled to obtain their blue blood for biomedical purposes. Although survivors are returned to the sea, up to 30% of the bled crabs may die.
In Japan, the horseshoe crab is known as the helmet crab, because its shell resembles a samurai helmet. In Europe, these arthropods are called horseshoe crabs.
Despite their warlike name, these are quite harmless animals; they do not use their tail spike for either defense or attack. This part of the body can serve as a rudder, and if a horseshoe crab accidentally turns over on its back, it pushes off the ground with its tail spike and returns to its original position.
Horseshoe crabs have amazing and numerous legs: six pairs of limbs are located on the cephalothorax and seven pairs on the abdomen. Five pairs of legs are used for walking, five pairs (males have four) end in claws, that is, they perform additional functions if necessary. In addition, the legs of the horseshoe crab are equipped with chewing processes, and in addition to their main purpose, they serve to capture food and grind it. The first pair of abdominal legs is involved in the process of reproduction, and five have gill petals, that is, horseshoe crabs also breathe thanks to their legs.
Also, the active movement of the gill petals helps the animals while swimming, although only young horseshoe crabs swim and only after turning over on their backs.
Horseshoe crabs have four eyes. One pair detects only movement, the second is more complex: these eyes see in more detail. And yet, horseshoe crabs do not have the blood we are used to, saturated with red hemoglobin; oxygen is carried by blue hemocyanin.
Horseshoe crabs are true living fossils that have changed little over the past few hundred million years. Among their unique features are their eyes, which protrude from the outside of a large shell while the rest of the animal is tucked inside. A new paper describes the unique design of the horseshoe crab’s eyes, which sets it apart from other animals.
Now the authors of a new article in the journal Advanced Science have figured out the structure of the visual organ of the horseshoe crab Limulus polyphemus in all its details. As befits an arthropod (especially one leading an active lifestyle), the horseshoe crab has complex eyes. In them, visual acuity is achieved by combining a number of simple eyes that work like lenses and collect light at different angles and transmit it to light-sensitive cells.
Goblin shark (Mitsukurina owstoni)
In 1898, scientists discovered an unusual shark in the Gulf of Aqaba in the Red Sea. Due to its resemblance, the goblin shark was mistaken for a preserved specimen of the Scapanorhynchus shark from the Cretaceous period, but it was later discovered to be an entirely different species. The goblin shark is a rare and fearsome species of deep-sea fish. Found in the Pacific, Atlantic, and Indian Oceans, this ancient species first appeared 125 million years ago. The goblin shark has a couple of unique adaptations that make it a deadly predator, such as a long, flat snout that is filled with electroreceptors, allowing it to sense the electrical fields of its prey. It also has a jaw filled with teeth attached to ligaments; these teeth can extend out of its mouth to grab prey when it bites.
Goblin sharks have been swimming in the Earth’s oceans for 125 million years. George Melin
The goblin shark has a flabby body covered in pink skin and can grow up to 13 feet (4 m) long and weigh up to 460 pounds (210 kg). Its fins are small and it moves more slowly than other shark species.
The goblin shark is a fascinating species that lives in the open ocean from the surface to depths of at least 4,265 feet (1,300 m). Like many species that have deep-sea origins, scientists believe that goblin sharks only come to the surface at night and spend most of their lives in the dark. The species is known for its fearsome appearance and ability to completely open its jaws while feeding.
The most noticeable physical features of the goblin shark are its long snout (called the rostrum) and its teeth. The rostrum is covered with specialized organs that help these sharks find prey in the low-light conditions of their favorite habitat by sensing the electric field created by other fish. The teeth are long and jagged, and the goblin shark is one of the very few shark species whose teeth are visible when the mouth is completely closed. In other words, goblin sharks cannot fit all of their teeth in their mouth.
Live goblin sharks have only been observed occasionally and almost never captured on film, so most of what scientists know about this species comes from accidental captures in fisheries that target other species. They are thought to be active predators, taking a range of fish, as well as squid and pelagic crustaceans. When hunting, they identify prey beneath their sensitive rostrum and extend their jaws far from their mouths to grab what they find. When feeding in this manner, they look more like something out of an Alien movie than a shark.
Goblin sharks mate via internal fertilization and give birth to a small number of relatively large young. Although they give birth to live young, these sharks do not bond with their young via a placenta. Instead, during the gestation period, the mother likely provides her young with unfertilized eggs, which they actively consume for nutrition. After birth, the young goblin sharks are ready to become active predators. The goblin shark is not commercially fished and is only occasionally caught by accident in fisheries targeting other species. Based on a recent analysis, scientists believe the goblin shark is a species of least concern.
Perhaps, the goblin shark is rightfully considered one of the most mystical and little-studied animals. You can find terrifying photos and videos on the Internet, after which you probably won’t want to meet this sea creature. Although this is unlikely, because this type of shark lives at a depth of 300 to 1300 meters, is found in warm and temperate waters of the Atlantic and Indian Oceans, as well as near Africa and California.
Another interesting fact: the goblin shark is reddish-pink in color, as the blood vessels show through the translucent skin. And another quarter of the shark’s body mass is taken up by the liver, which serves as a swim bladder.
Scientists do not yet have enough information to say with certainty whether this species is endangered or not. The shark has no commercial value, and does not pose a danger to humans due to its deep-sea habitat. However, warming ocean waters are changing the aquatic system in many ways, and the goblin shark may move to shallow waters in the coming years.
Platypus (Ornithorhynchus anatinus)
The platypus is an aquatic-adapted mammal that first appeared more than 110 million years ago during the Cretaceous Period (145–66 million years ago). A 2008 study published in the journal Nature found that the platypus’s genetic code is a mix of mammalian, avian, and reptilian genes.
Platypuses first appeared in the Cretaceous period, at the same time as dinosaurs. John Carnemolla
The platypus is a very strange animal. It lays eggs, has poisonous spurs, detects electrical signals and is completely toothless, but it does have a beak.
When the platypus skin was first brought to England at the very end of the 18th century, scientists initially thought it was something like a beaver with a duck beak sewn onto it. At that time, Asian taxidermists were making many such chimeric creations (the most famous example is the mermaid from Fiji). Having finally convinced themselves that the animal was real, zoologists could not decide for another quarter of a century whether to classify it as a mammal, a bird, or even a separate class of animals. The confusion of British scientists is understandable: the platypus is a mammal, but a very strange one.
First, the platypus, unlike normal mammals, lays eggs. These eggs are similar to the eggs of birds and reptiles in the amount of yolk and the type of zygote cleavage (which is related to the amount of yolk). However, unlike bird eggs, platypus eggs spend more time inside the female than outside: almost a month inside, and about 10 days outside. When the eggs are outside, the female “hatches” them, curled up in a ball around the clutch. All this happens in a nest that the female builds from reeds and leaves in the depths of a long brood burrow. When hatching from an egg, little platypuses help themselves with an egg tooth – a small horny tubercle on the beak. Birds and reptiles also have such teeth: they are needed to break through the egg shell and fall off soon after hatching.
Secondly, the platypus has a beak. No other mammal has such a beak, but it also does not look like a bird’s beak at all. The platypus’s beak is soft, covered with elastic skin and stretched over bony arches formed on top by the premaxillary bone (in most mammals, this is a small bone on which the incisors are located) and on the bottom by the lower jaw. The beak is an organ of electroreception: it picks up electrical signals generated by the contraction of the muscles of aquatic animals. Electroreception is developed in amphibians and fish, but among mammals, only the Guiana dolphin has it, which, like the platypus, lives in muddy water. The platypus’s closest relatives, the echidnas, also have electroreceptors, but they apparently do not use them much. The platypus uses its electroreceptor beak for hunting, swimming in the water and waving it from side to side in search of prey. It does not use sight, hearing or smell: its eyes and ear openings are located on the sides of its head in special grooves that close when diving, just like the valves of its nostrils. The platypus eats small aquatic animals: crustaceans, worms and larvae. It also has no teeth: the only teeth in its life (only a few on each jaw) wear out a few months after birth. Instead, hard horny plates grow on the jaws, with which the platypus grinds its food.
The platypus is also poisonous. However, it is not so unique in this: there are several other poisonous species among mammals – some shrews, solenodons and slow lorises. The platypus secretes poison from horny spurs on its hind legs, into which the ducts of the poisonous femoral glands exit. These spurs are present in young animals of both sexes, but soon fall off in females (the same thing, by the way, happens with the spurs of echidnas). In males, the poison is produced during the breeding season, and they kick with their spurs during mating fights. The basis of the platypus’s poison is proteins similar to defensins – peptides of the mammalian immune system designed to destroy bacteria and viruses. In addition to them, the poison contains many other active substances, which in combination cause intravascular blood clotting, proteolysis and hemolysis, muscle relaxation and allergic reactions in the bitten person.
Also, as it turned out recently, platypus venom contains glucagon-like peptide-1 (GLP-1). This hormone, produced in the intestines and stimulating the production of insulin, is present in all mammals and usually, after entering the bloodstream, is destroyed within a few minutes. But not in the platypus! In the platypus (and the echidna), GLP-1 lives much longer, and therefore, as scientists hope, in the future it can be used to treat type 2 diabetes, in which the usual GLP-1 “does not have time” to stimulate insulin synthesis.
Platypus venom can kill a small animal like a dog, but is not fatal to humans. However, it causes severe swelling and excruciating pain, which develops into hyperalgesia – an abnormally high sensitivity to pain. Hyperalgesia can persist for several months. In some cases, it does not respond to painkillers, even morphine, and only a blockade of the peripheral nerves at the site of the bite helps to relieve pain. There is no antidote yet. Therefore, the surest way to protect yourself from platypus venom is to be wary of this animal. If close contact with a platypus is unavoidable, it is recommended to lift it by the tail: such advice was published by an Australian clinic after a platypus stung an American scientist trying to study it with both of its spurs at once.
Another unusual feature of the platypus is that it has 10 sex chromosomes instead of the usual two for mammals: XXXXXXXXXX in the female and XYXYXYXYXY in the male. All these chromosomes are linked into a complex, which behaves as a single whole during meiosis, so males produce two types of sperm: with XXXXX chains and with YYYYY chains. The SRY gene, which in most mammals is located on the Y chromosome and determines the development of the organism according to the male type, is also absent in the platypus: this function is performed by another gene, AMH.
The list of platypus oddities can go on and on. For example, the platypus has mammary glands (after all, it is a mammal, not a bird), but it has no nipples. Therefore, newborn platypuses simply lick milk from the mother’s belly, where it flows out through enlarged skin pores. When the platypus walks on land, its limbs are located on the sides of the body, like reptiles, and not under the body, like other mammals. With this position of the limbs (it is called parasagittal), the animal seems to continuously push itself up, spending a lot of energy on this. Therefore, it is not surprising that the platypus spends most of its time in the water, and when on land, it prefers to sleep in its burrow. In addition, the platypus has a very low metabolism compared to other mammals: its normal body temperature is only 32 degrees (however, it is warm-blooded and successfully maintains body temperature even in cold water). Finally, the platypus gets fat (and thinner) in its tail: it is there that, like the Tasmanian devil, it stores fat reserves.
Amami Rabbit (Pentalagus furnessi)
The Amami rabbit is a dark-furred species and the last living remnant of primitive rabbit species that became extinct on the Asian mainland during the Pleistocene Era (2.6 million to 11,700 years ago). It is now found only on two small islands off the coast of Japan and is an endangered species with only 5,000 individuals remaining. A forest and burrow dweller, the Amami rabbit is small in size and has a distinctive appearance with short ears and long claws.
Amami rabbits retain primitive features typical of species that lived hundreds of thousands of years ago. TokioMarineLife
Lives on the ground, climbs very poorly. Uses long claws to dig holes. Feeds on plant food. Is the last representative of its genus, long extinct in continental Asia. Population no more than 5 thousand individuals. The main threat is deforestation, predation by cats, dogs and introduced mongooses.
Climbing hares are nocturnal animals. They generally avoid people. However, domesticated hares are kept on the islands. They can also be seen at the Kagoshima City Zoo.
They grow up to 45 centimeters in length, gaining only 2-2.5 kilograms of weight, and females of this species are always slightly larger. Although they climb steep slopes with dexterity – long claws on short paws help with this. With them, amami digs one and a half meter holes. Moreover, shelters for rest and reproduction are built separately.
Nautilus (Nautilus pompilius)
Nautiluses are cephalopods, or marine mollusks, and one of the oldest types of “living fossils” on Earth. These spiral-shelled creatures have changed little since they first appeared more than 500 million years ago during the early Paleozoic Era (541–252 million years ago). Found in the western Pacific and Indian Oceans, the nautilus lives in a large chamber in its hard shell and uses jet propulsion to swim and feed in the ocean.
Nautiluses are the oldest “living fossils” on Earth, dating back hundreds of millions of years. Alexey Permyakov
Nautilus pompilius is the most numerous species of the genus Nautilus. Their first ancient relatives, who came to us from the distant Cambrian (about half a billion years ago), reached their peak in the Paleozoic (after about 250 million years). Representatives of these ancient cephalopods had colossal dimensions: 3.5 m versus 25 cm for their current descendants.
Modern nautiluses have taken a fancy to the warm waters of the Indian and Pacific Oceans, where they are found from the very surface to depths of over half a kilometer; they absolutely cannot stand fresh water.
The incredible-looking nautilus shells were known in Ancient Greece, but the shell’s “owner” was shrouded in mystery until 1892. That year, a live nautilus was delivered from the Pacific Ocean to zoologist and paleontologist Richard Owen at his request. The inquisitive scientist immediately began studying it and discovered that the nautilus was none other than a mollusk with many arms, whose body was hidden in a very remarkable shell.
The spiral “house” of the mollusk consists of 38 chambers and is “built” according to a complex mathematical principle (the law of logarithmic progression). All chambers, except for the last and largest, where the body of the nautilus with ninety “legs” is located, are connected through holes by a siphon. Through the work of the latter, the shell performs different functions – when gases enter the chambers through the siphon and fill the shell with them, the “boat” gains positive buoyancy and easily floats. And vice versa, when gases are pumped out in the same way, the “house” of the mollusk gains negative buoyancy and the mollusk sinks into the ocean.
It is interesting that the nautilus moves “blindly”, backwards, not seeing or imagining the obstacles that may be in its path. The nautilus shell is two-layered: the upper (outer) layer is porcelain-like – it really does resemble fragile porcelain, and the inner layer, with a mother-of-pearl shine, is mother-of-pearl. The nautilus “house” grows together with the owner, who moves into a more spacious chamber as the shell grows.
An empty shellfish home after its death can be found far from its habitat – after the death of the “owner” their shells remain afloat and move at the mercy of the waves, winds and currents.
Nautiluses prefer to “hover” in the depths of quiet waters, and move along the bottom in small groups, using their many “arms”. Using their keen sense of smell (nautiluses have very primitive eyes) and beak-like jaws, the “boats” hunt, mainly at night, for small fish and crustaceans.
And another amazing quality of these ancient inhabitants of the Earth is that they have amazing regeneration: literally in a few hours, the wounds on their bodies heal, and if a tentacle is lost, a new one quickly grows back.
Nautiluses are dioecious animals. When the time comes, the future “parents” go to a depth of two hundred meters somewhere in a well-warmed water area. The female, after fertilization, glues large eggs, up to 4 cm in diameter, to underwater protrusions. About a year later, small copies of the “parents” with a body length of no more than 3 cm and only one chamber emerge from the eggs. By the way, it has been established that nautiluses can live more than 17 years – and this is much longer than their “tribesmen” – cephalopods.
Komodo dragon (Varanus komodoensis)
The Komodo dragon is an ancient, venomous reptile that has been around for millions of years. It lives in the Lesser Sunda Islands of Indonesia, including Komodo Island. Scientists have discovered that its similar ancestors evolved in Australia about 100 million years ago. The world’s largest lizard can grow up to 10 feet (3 m) long and weigh up to 330 pounds (150 kg). This dominant predator can eat up to 80% of its body weight in a single meal.
Komodo dragons are the largest lizards in the world, growing up to 10 feet in length. Jamie Lamb
Komodo dragons, which inhabit the islands of Indonesia, are in fact the largest predators on these islands. They hunt pigs, deer and Asian buffalo. 75% of pigs and deer die from a bite of a monitor lizard within 30 minutes from blood loss, another 15% – after 3-4 hours from the poison secreted by its salivary glands.
The Komodo dragon has a rather menacing appearance. Its body is covered with small plate-like scales called osteoderms. The Komodo dragon is dark in color, mostly brown, with small spots and yellow inclusions.
The Komodo dragon is an impressive size. The body length is usually between 2.2 and 2.6 meters. The average weight of Komodo dragons is between 35 and 60 kilograms. An interesting fact about Komodo dragons is that males are significantly larger than females and it is not uncommon to find individuals with a body length of 3 meters and a weight of over 70 kilograms.
Giant lizards are often seen digging up graves. Komodo dragons are scavengers. They often disturb people who live on the same islands as them by digging up shallow burials.
When hunting, the Komodo dragon uses almost all parts of its body: paws with huge and sharp claws, jaws with razor teeth, and even a tail. Due to the fact that half the length of this predator’s body is the tail, it successfully uses it as a formidable weapon. An adult Komodo dragon can break the legs of large ungulates with a blow of its tail, thereby depriving them of an attempt to escape or the ability to resist.
The Komodo dragon kills its victims with the help of two glands in the lower jaw that produce poison. This toxin causes muscle paralysis and hypothermia in the victim, impairs blood clotting and lowers blood pressure, which leads to shock and loss of consciousness of the victim. Of course, all this is possible only with a large amount of poison in the wound. For example, 4 milligrams of poison will be enough to make a deer weighing more than 40 kilograms faint. But even with a small amount of toxin in the blood, the victim will feel unwell, which, together with the blood loss from the wound, reduces its chance of survival to zero.
Female giant lizards can reproduce asexually if they have not found a male. This method of reproduction is called parthenogenesis. In this case, only females can be born. However, they always prefer sexual reproduction if the opportunity arises.
Purple frog (Nasikabatrachus sahyadrensis)
The purple frog, also called the pig-nosed frog, is a rare species of amphibian belonging to the family Nasikabatrachidae. It has evolved independently for 100 million years. Scientists discovered the species in the Western Ghats of India in 2003. Spending most of its life underground, the purple frog briefly surfaces to breed. The purple frog has a bloated body, short legs, and a small head.
Purple frogs, also known as pig-nosed frogs, were discovered in 2003. They have evolved independently for 100 million years. Nature Picture Library
The purple frog is the only species of purple frog belonging to the Seychelles frog family. The official discovery and classification of this species took place only in 2003. Its Latin name comes from the word “nasika”, which means “nose” in Sanskrit.
The purple frog’s body has a slightly unusual shape. It is rounder than other frog species. Its small head compared to its body and the pointed shape of its white muzzle are striking. Adults are purple, but in the belly area its smooth skin takes on a grayish tint. These frogs grow up to 7-9 centimeters.
These amphibians lead a completely underground lifestyle. They need a humid environment to live comfortably. Therefore, they dig deep holes for themselves, which can go into the ground to a depth of 1.3-3.7 meters.
The underground lifestyle and the specific structure of the head (a narrow head with a small mouth) influenced the diet of this frog. Its main food is termites. It simply cannot swallow larger insects. The frog easily pushes its narrow muzzle into various underground niches and passages, and its ribbed tongue helps it suck its prey out of these holes.
In the underground world, a frog does not need good eyesight, but an excellent sense of touch helps it detect and locate prey. In addition to termites, it can snack on ants and small worms.
These amphibians come to the surface only during the monsoon season, for reproduction. Perhaps that is why it remained an unknown species for the scientific world for a long time. Although local residents have known about it for a long time, scientists treated their words with a degree of skepticism until 2003, until they themselves confirmed its existence.
Laotian Rock Rat (Laonastes aenigmamus)
First discovered in 2005 in Laos, the Laotian rock rat is the last surviving member of an ancient fossil family, Diatomyidae, which is thought to have gone extinct 11 million years ago. Nicknamed the “squirrel rat,” the ancient species has dark fur and resembles a rat, but with a bushy squirrel tail.
Known to local Laotian villagers as the ga-nu, the animal was first described in April 2005 in the scientific journal Systematics and Biodiversity. Mistakenly identified as a member of an entirely new family of mammals, the rock rat has captured the attention of scientists around the world.
Dr Dawson’s paper describes the rock rat as an example of the “Lazarus effect” – named after the biblical figure who rose from the dead. Biologists use the term for the rare occasions when a species thought to be extinct is discovered.
Professor Redfield has long studied wildlife and organized the expedition to Laos on his own. With the help of guides and local hunters, after many unsuccessful attempts, he managed to catch and film this rare animal on May 17 near the Laotian village of Doi, not far from the border with Thailand. After filming, the rock rat was released into the wild.
The first photographs and video of the small, furry animal, thought to have been extinct for more than 11 million years, were taken by Florida State University professor David Redfield and Thai biologist Uthai Treesucon, Terradaily reports. The photo shows a “living fossil” — a Laotian rock rat (Petromys).
The film, shot by Professor Redfield, shows a calm animal the size of a squirrel, covered in dark, fluffy fur with a long, but not as large as a squirrel’s, tail. Biologists were especially amazed that this animal walks like a duck. The rock rat is completely unsuited to climbing trees – it slowly waddles on its hind legs, turned inward.
Cockroach (Order Blattodea)
Cockroaches belong to one of the oldest orders of insects, Blattodea, which consists of cockroaches and termites. Fossils of early cockroaches date back more than 300 million years, to the Upper Carboniferous period. There are about 4,000 species of cockroaches found worldwide, and they are similar to their fossil cousins.
When a rock now known as the Chicxulub impactor fell from space and slammed into Earth 66 million years ago, there were cockroaches in the area. The impact caused a massive earthquake, and scientists believe it also triggered volcanic eruptions thousands of miles away. Three-quarters of the plants and animals on Earth died, including all but a few dinosaurs that were the ancestors of modern birds.
How could inch-long cockroaches survive when so many powerful animals died out? It turns out they were well equipped to survive the meteorite disaster.
If you’ve ever seen a cockroach, you’ve probably noticed that its body is very flat. This is no accident. Flatter insects can squeeze into tighter spaces. This allows them to hide almost anywhere — and may have helped them survive the Chicxulub encounter.
Cockroach in Western Australia. Oxford Scientific
Many animals had nowhere to run, but cockroaches could take refuge in tiny cracks in the soil, which provided excellent protection from the heat.
The meteor strike caused a cascade of effects. It kicked up so much dust that the sky darkened. As the sun dimmed, temperatures dropped, and winter conditions became common around the world. With little sunlight, surviving plants struggled to grow, and many other organisms that depended on those plants starved.
But not cockroaches. Unlike some insects that prefer to feed on one specific plant, cockroaches are omnivorous scavengers. This means they will eat most foods that come from animals or plants, as well as cardboard, some types of clothing, and even feces. Their unfussy appetites have allowed cockroaches to survive the hard times following the Chicxulub extinction and other natural disasters.
Another useful trait is that cockroaches lay their eggs in small protective containers. These cardboard egg cases look like dried beans and are called ootheca, which means “egg container.” Like phone cases, ootheca are hard and protect their contents from physical damage and other threats like flooding and drought. Some cockroaches may have waited out part of the Chicxulub disaster, tucked comfortably inside their ootheca.
Modern cockroaches are tiny survivors that can live almost anywhere on earth, from the heat of the tropics to some of the coldest corners of the globe. Scientists estimate that there are more than 4,000 species of cockroaches.
Aardvark (Orycteropus afer)
The aardvark is a nocturnal and solitary mammal native to Africa that first appeared more than 50 million years ago, according to fossil records. The last remaining member of the ancient order Tublidentata, the species has not evolved much in that time, making it a living fossil. Aardvark translates to “earth pig” in Afrikaans, as its body resembles that of a pig, although the species is most closely related to the elephant.
Aardvarks have barely evolved in the last 50 million years. Martin Harvey
The aardvark looks like a pig with an elongated snout, hare ears and a strong muscular tail, similar to a kangaroo’s tail. It got its name from the peculiar structure of its molars, which consist of fused tubes, lack enamel and roots and are constantly growing. The aardvark’s tongue, thin and sharp, reaches 45 cm in length. At one time, Dutch colonists gave this animal the nickname “aardvark”, which means “earth pig”, since the aardvark digs holes perfectly and is considered one of the best “diggers” in the world. It digs a hole 60 cm deep in less than 15 seconds.
The aardvark is timid: at the slightest suspicious rustle it hides in a hole or burrows. It leads a solitary life. It is active at night, but can occasionally be seen basking in the sun near its hole. The resting hole can be up to 3 meters long, and the breeding holes are four times longer. Life expectancy is about 10 years.
The aardvark lives in open sparse forests, savannas, and soft-soil shrublands on the African continent. Its food includes termites, ants, beetle larvae, locusts, and other orthopterans, and according to some sources, mushrooms, fruits, and berries. In one night, the aardvark can eat up to 50,000 termites.
Aardvarks are presumably polygamous. Pregnancy lasts about 7 months and ends with the birth of one, rarely two cubs. They do not leave the burrows for up to 2 weeks, and later accompany their mother on night feedings. At the age of 6 months, young aardvarks already dig their own burrows. Sexual maturity occurs at 2 years. In the wild, they can live up to 18 years, in captivity – up to 24 years.
Ginkgo tree (Ginkgo biloba)
Having survived dinosaurs and the Hiroshima atomic bomb, the ginkgo tree, also known as the maidenhair tree, is an incredibly resilient—and smelly—tree species. Fossilized ginkgo leaves show that they have changed little in over 200 million years. This living fossil is one of the oldest tree species in the world and the last surviving member of a group of trees that existed before dinosaurs roamed the Earth.
Ginkgo trees have changed little in 200 million years. Istvan Balogh
Ginkgo biloba is a deciduous plant with a unique leaf shape for modern gymnosperms – a fan-shaped two-lobed blade 5-8 cm wide, on a thin petiole up to 10 cm long. Veins with dichotomous branching. Leaves develop on long shoots singly and quickly, or on shortened shoots in groups of two to four slowly.
The tree in adulthood is up to 40 m high and the trunk diameter is up to 4.5 m. The crown is initially pyramidal, expanding with age.
Summer green leaves, smooth on both sides, leathery, up to 6 cm long and 5-8 cm wide. It has green foliage, fan-shaped, located close together. It is the foliage that gives the bush its curliness. Young shoots are relatively short, thick, stocky, grow slightly drooping, leaf buds on them are located very densely. Ginkgo leaves are botanically classified as needles.
Prefers a sunny place, tolerates light partial shade. Resistant to heat and sunburn. Develops quickly on drained, loamy, fertile soil. Average winter hardiness. Zone 5 – up to -29 °C.
Pike (family Lepisosteidae)
Prehistoric fish with giant jaws full of razor-sharp teeth are true living fossils. Gars have the slowest rate of evolution of all jawed vertebrates, having changed little since they first appeared in the time of the dinosaurs.
Scientists have found that pike are the most living fossils because they have changed incredibly slowly since their ancestors emerged during the age of dinosaurs 150 million years ago. This slow rate of change means that these prehistoric fish have the slowest rate of molecular evolution of any jawed vertebrate.
The lineage of pikes (family Lepisosteidae) extends over thousands of years, with the most anatomically modern species appearing in the fossil record during the late Jurassic period (163.5–145 million years ago). Seven living species inhabit lakes and rivers in North and South America, and one species occasionally ventures into marine environments.
In a new study published in the journal Evolution, scientists studied gar and other species called living fossils — organisms that remain unchanged for long periods of time.
Longnose gars can interbreed with alligator gars, despite the fact that they diverged 100 million years ago. JA Dunbar
The term is controversial because, although many such species resemble their fossil relatives, they have actually undergone evolutionary changes, even if the changes aren’t immediately obvious. To be a living fossil, an organism must share ancient common ancestry with extinct lineages, change little in physical form compared to its fossil relatives, and have diversified into a relatively small number of related species, lead author Chase Brownstein, a first-year graduate student at Yale, told Live Science.
The researchers used computer analysis to examine the sequences of genes that were preserved from common ancestors (called orthologs), revealing the rate at which genes were replaced or mutated over time.
The study found that some animals considered living fossils, such as the tuatara (Sphenodon punctatus), coelacanth (Latimeria chalumnae) and hoatzin (Opisthocomus hoazin), differ significantly from their fossil relatives, although they retained many of their characteristics.
However, pike and related sturgeons appear to have evolved even more slowly.
Of the 471 species studied, pike and sturgeon had the slowest rates of replacement. Pike appear to be evolving at rates up to three orders of magnitude slower than any other living vertebrate.
The study found that alligator gar have one of the slowest rates of evolution of any jawed vertebrate. Jennifer White Maxwell
Substitutions result in physical changes. Thus, the low rates of substitution in this group of fish correspond to low rates of speciation—that is, the lineage did not diversify into a huge number of new, physically distinct species, as it did in other groups. Instead, the few species that did emerge remained stable for long periods.
They evolved so slowly that two species separated by 100 million years of evolution can still interbreed. Alligator gars (Atractosteus spatula) and longnose gars (Lepisosteus osseus) have been known to interbreed in rivers in Texas and Oklahoma. Other gar species also produce hybrids. Even stranger, these hybrids are often fertile.
Interestingly, longnose and alligator gars do not appear to have hybridized significantly during their evolutionary history, despite sharing the same habitat for about 55 million years. Hybrids may be occurring now because the two species are forced to share spawning grounds in certain river floodplains, according to the study.