Over 99% of all species that have ever existed on Earth are now extinct. As we confront a growing number of species currently under threat, it's crucial to reflect on the incredible creatures we've already lost — some at the hands of humankind. From the gigantic land mammals of the ancient past to the smallest creatures lost to climate change, each entry reminds us of the urgency of conservation.

Click through the gallery to find 40 extinct animals we'll never see again...

Trilobites first appeared around 520 million years ago in marine environments worldwide, making them 290 million years older than the first dinosaurs. These early arthropods had segmented bodies and hard exoskeletons, up to a foot (30cm) in length. They survived on Earth for more than 250 million years. In contrast, humankind has only been around 0.1% as long as trilobites lasted.

Dunkleosteus roamed the oceans around what is now North America, Europe and Morocco from 358 to 382 million years ago. This giant fish grew up to 33 feet (10m) in length, had an armour-plated head, but lacked true teeth – instead it had two long bony blades that could snap and crush its prey. They ate sharks and were even cannibalistic. Experts believe Dunkleosteus may have been one of the earliest creatures to exist as male or female, meaning that pairs had to mate physically.

Living between 286 and 270 million years ago, Dimetrodon inhabited swampy regions of North America and Europe. Measuring about 11.5 feet (3.5m) long, this predator featured a sail-like spine on its back. Although it predates dinosaurs and mammals, it has no modern relative. Its sail is believed to have played a role in regulating body temperature, as evidenced by well-preserved fossils.

Pteranodon, a genus of pterosaurs, soared the skies over North America around 90-100 million years ago. With wingspans 23 feet (7m) or more, these flying reptiles had long, toothless beaks. Their closest living relatives are birds, and fossils found in Kansas reveal much about their flight mechanics and lifestyle.

Follow us on Facebook for more animal features and travel inspiration

Mosasaurus lived around 70 million years ago in the Late Cretaceous period. This marine reptile could grow up to 56 feet (17m) long and had a robust body and powerful jaws, similar to modern monitor lizards. Fossils, primarily found in Europe and North America, showcase its adaptation to marine life and its role as a top predator in ancient seas.

Quetzalcoatlus, one of the largest known flying animals, lived around 70-65 million years ago. With a wingspan exceeding 30 feet (9m), it soared over what is now North America. Quetzalcoatlus fossils, especially those found in Texas, reveal that it equalled the large birds of today in its flying prowess.

Triceratops lived in North America about 68-66 million years ago. This herbivorous dinosaur had a large bony frill and three facial horns, growing up to 30 feet (9m) long. Similar to modern rhinoceroses in behaviour, Triceratops fossils offer a window into the herbivorous life of the late Cretaceous period.

Every five-year-old’s favourite dinosaur, the T-Rex, dubbed the 'king of the dinosaurs', roamed the Earth during the late Cretaceous period, around 66 million years ago. This apex predator dominated the food chain and is defined by its massive size, powerful jaws and ridiculously tiny arms. The T. Rex is believed to have faced extinction during the Cretaceous-Paleogene event, possibly due to climate change or a catastrophic asteroid impact.

That's right: the Meg! Megalodon was a giant shark that lived from 23 to 3.6 million years ago and inhabited warm oceans worldwide. Reaching lengths of up to 60 feet (18m), it preyed on whales and large fish. Bearing a resemblance to the modern great white shark, Megalodon teeth, often the size of a human hand, are frequently found in marine sediments, showcasing its formidable presence.

Discover the best wildlife experiences in the world

Diprotodon, the largest known marsupial, lived in Australia from about 1.6 million to 46,000 years ago. It resembled a giant wombat and could grow as large as a rhinoceros. Its fossils, discovered widely across Australia, show its significant presence in Pleistocene megafauna.

This is where it gets personal. Neanderthals, as they’re better known, lived in Europe and western Asia from about 400,000 to 40,000 years ago. Stockier and more robust than modern humans, they had distinct brow ridges and larger noses. Neanderthal fossils and archaeological sites reveal their complex tool use, social structures and interactions with early homo sapiens.

The American lion roamed North America during the Pleistocene epoch, from about 340,000 to 11,000 years ago. Larger than modern lions, it stood around four feet (1.3m) at the shoulder and weighed up to 450kg (1,000lbs). Fossils, particularly from the La Brea Tar Pits in Los Angeles, reveal its similarities to today's big cats and its role as a top predator.

Glyptodon, a giant armadillo-like creature, lived in South America until about 10,000 years ago. Weighing up to 900kg (2,000lbs), it had a large, domed shell for protection. Related to modern armadillos, Glyptodon fossils found in Argentina and Brazil reveal much about its defensive adaptations and ancient environment.

Mastodons roamed North and Central America from about 27 million to 10,000 years ago. These prehistoric relatives of elephants stood around 10 feet tall (3m) tall and were covered in long, shaggy hair. Mastodons were akin to modern elephants but had distinct, blunt-tipped tusks and different molar shapes adapted for chewing leaves and branches. Numerous well-preserved mastodon skeletons have been unearthed in peat bogs and tar pits.

Smilodon, commonly known as the sabre-toothed cat, lived in the Americas from 2.5 million to 10,000 years ago. Weighing up to 280kg (620lbs), it had long, curved sabre-like canine teeth. Smilodon resembles modern big cats, like lions and tigers, but is distinct for its powerful forelimbs and elongated fangs. Many fossils have been discovered in the La Brea Tar Pits in Los Angeles, providing significant insight into this fierce predator's life.

Megatherium, the giant ground sloth, lived in South America until about 10,000 years ago. This massive herbivore, reaching up to 20 feet (6m) in length, resembled modern sloths but was much larger. Fossils from Argentina provide a glimpse into its slow-moving life and unique adaptations for a herbivorous diet.

The woolly mammoth lived from 400,000 to 4,000 years ago across Europe, Asia and North America. Similar in size to modern elephants, it was covered in long, shaggy hair to withstand the Ice Age's frigid temperatures. Fossils of these creatures are often found in Siberian permafrost, revealing well-preserved specimens. Modern elephants are their closest living relatives.

The Irish elk, or Megaloceros giganteus, lived across Eurasia from about 400,000 to 8,000 years ago. Known for its enormous antlers, which could span up to 12 feet (3.6m), it resembled modern deer but was much larger. Fossils, especially well-preserved in peat bogs, highlight its impressive size and the striking features of this magnificent herbivore.

The moa, native to New Zealand, became extinct around AD 1400. These flightless birds, related to modern-day kiwis, were some of the largest birds that ever existed, with some species reaching heights of 12 feet (3.6m). Overhunting by early Polynesian settlers and habitat destruction led to their rapid extinction.

This massive wild cattle species, which once roamed across Europe, Asia, and North Africa, is considered to be the wild ancestor of modern domestic cattle. Standing over six feet (1.8m) tall at the shoulders, it played a crucial role in ancient cultures and mythology. Hunted extensively for its meat and targeted as a symbol of strength in medieval hunts, the auroch gradually disappeared. The last recorded Auroch died in 1627 in Poland, marking the extinction of this majestic bovine species due to human exploitation and habitat loss.

The archetypal simile for extinction at the hands of human ignorance, the dodo, a flightless bird native to Mauritius, has been ‘as dead as a dodo’ since the late 17th century. It stood about three feet (0.9m) tall and had a distinctive large beak. Resembling modern pigeons and doves, the dodo fell victim to introduced species and human exploitation. Its extinction was confirmed by fossil remains and accounts from early explorers, making it an enduring symbol of human-induced extinction.

Check out beautiful images from the Bird Photographer of the Year awards

Steller's sea cow, a massive marine mammal, lived in the Bering Sea until its extinction in the 18th century. Growing up to 30 feet (9m) long, it resembled a large, docile manatee. Overhunting by humans led to its rapid extinction within 27 years of its discovery by Europeans in 1741.

The great auk was a flightless bird native to the North Atlantic, extinct by the mid-19th century. Standing about 30 inches (76cm) tall, it resembled modern penguins but was more closely related to puffins. Overhunting for its feathers and eggs led to its demise, with the last confirmed sighting in 1852.

Also known as the Falkland Islands Fox or Warrah, this was the only native land mammal on the Falkland Islands. Isolated from mainland predators, it evolved into a unique canid species. Hunted by settlers for its fur and considered a threat to livestock, the population quickly declined. The last known specimen was killed in 1876, making the Falkland Islands Wolf the first known canid species to be driven to extinction by humans.

The Labrador duck, native to eastern North America, was declared extinct in the late 19th century. This small sea duck, resembling other diving ducks, suffered from overhunting and habitat loss. The last confirmed sighting occurred in 1878, marking the end of this species.

The quagga, a striking subspecies of the plains zebra native to South Africa, featured a distinctive coat pattern with stripes fading towards its rear. Sometimes called the half-striped zebra, it was hunted relentlessly for its unique hide and faced rapid extinction. The last known wild quagga died in 1878, with the species officially declared extinct in 1883. Efforts to revive the quagga through selective breeding of plains zebras with similar coat patterns continue.

Gigarcanum, AKA Delcourt’s Giant Gecko, was the largest known gecko. Originally thought to be native to New Zealand, research in recent years has pointed to beginnings in New Caledonia. This elusive nocturnal reptile, likely reaching up to two feet (60cm) in length, thrived in forest habitats. It is thought that habitat destruction and the introduction of predators to its environment decimated its population. The species was identified from a single taxidermied specimen from the 19th century that was rediscovered in a French museum in the 1980s – but it had already become extinct, likely in the early 20th century.

Once abundant in North America, the passenger pigeon became extinct in 1914. These birds lived in enormous flocks, darkening the skies during migration. Like the modern mourning dove, they were driven to extinction by massive hunting and habitat destruction. The last known passenger pigeon, named Martha, died in captivity at the Cincinnati Zoo, symbolising a poignant loss of avian diversity.

The Tasmanian tiger, or thylacine, was a carnivorous marsupial native to Tasmania, Australia and New Guinea. It resembled a large dog with stripes and existed until the 1930s. Related to modern marsupials like the Tasmanian devil, the thylacine's decline was due to hunting, disease and habitat loss. The last known thylacine died in captivity in 1936, highlighting the fragility of isolated species.

The Caribbean monk seal, native to the Caribbean Sea and Gulf of Mexico, was declared extinct in the mid-20th century. These seals, like Hawaiian monk seals, were the only seal species native to the Caribbean. Overhunting for their blubber and habitat degradation led to their rapid decline and eventual extinction.

The Japanese Sea Lion, once found along Japan's coast, and identifiable by its brown fur and smaller size, was hunted for its meat, oil, and skin. Their numbers rapidly declined in the late 19th century, despite protection efforts that included bans on hunting. The last confirmed sighting was in 1974. Human exploitation and habitat loss contributed to its extinction, marking a tragic loss in marine biodiversity.

The golden toad, native to the cloud forests of Costa Rica, became extinct in the late 20th century. Its bright orange coloration made it a symbol of amphibian diversity. Likely driven to extinction by climate change and disease, the golden toad's disappearance highlighted the vulnerability of amphibian species to environmental changes.

The only species ever to become extinct more than once, the Pyrenean ibex, native to the Pyrenees mountains, first died out in 2000. Overhunting and habitat loss due to human activities led to its extinction, highlighting the challenges faced by isolated populations of wild animals. After many attempts in Spain, it became the first species to be brought back from extinction by cloning in July 2003. Unfortunately, the clone died just minutes after its birth due to a lung defect; making it the first species to become extinct twice.

Once thriving, with a large geographic range across Central Asia, the Caspian tiger was a formidable apex predator. Its demise began with the Russian colonisation of Turkestan during the late 19th century, when the tiger was systematically exterminated by the military, sports hunters and locals who were paid for tiger skins. By the mid-20th century, habitat loss, hunting and agricultural expansion led to its demise. It was officially declared extinct in 2003.

The baiji, or Chinese river dolphin, was native to the Yangtze River in China, where it suffered from pollution, habitat destruction and overfishing. The Baiji was not closely related to any living species of dolphin: it had a long beak and small eyes, adapted to murky waters. It is considered the first dolphin species driven to extinction due to the impact of humans. While the International Union for Conservation of Nature (IUCN) lists the dolphin as 'critically endangered: possibly extinct,' a live example of the species has not been found in 40 years.

The western black rhinoceros was declared extinct in 2011. Like Africa’s other rhino species, it was hunted for its horn. Rhinos are poached to meet the high demand for their horns in some Asian countries, where they are predominantly used in traditional Chinese medicine (TCM) but are increasingly used as a symbol of wealth. International trade in rhino horns has been banned since 1977, and anti-poaching initiatives continue. Rhinos, though, are still killed due to demand on the black market.

Endemic to the Galapagos Islands, the pinta giant tortoise was a significant species studied by Charles Darwin. Its population plummeted due to centuries of hunting, especially by whalers in the 19th century. The subspecies was assumed extinct by the mid-20th century, until a single male was discovered in 1971. Attempts were made to mate Lonesome George, the last known individual of the species, with similar subspecies, but they were unsuccessful. Lonesome George died alone in June 2012.

Discovered in 1845, this small rodent, native to Bramble Cay in the Great Barrier Reef, was notable for its unique adaptation to a tiny coral cay environment. However, rising sea levels and increased storm surges led to habitat loss, ultimately causing its extinction. Last seen in 2009, it was formally declared extinct by the IUCN in May 2015. It is officially the first mammal to become extinct due to human-induced climate change.

The Javan tiger, native to the Indonesian island of Java, was officially declared extinct in 2008. However, it had not been found in the wild for decades beforehand. Its population was driven to extinction due to habitat loss and hunting. In August 2019, a local in West Java claimed to have glimpsed one. A single hair was recovered from the scene, and DNA analysis in 2022 concluded that it belonged to a Javan tiger. Whether the Javan tiger actually still occurs in the wild needs to be confirmed with further genetic and field studies.

Native to eastern and southern China, and northern Vietnam, the Yangtze giant softshell turtle – with just one male living in capacity – was declared functionally extinct in 2019. Perhaps the largest living freshwater turtle in the world, they are identifiable by their pig-like snouts. Faced with habitat loss, pollution, and illegal trade, its population is estimated to have declined by 99% over the past 200 years. In October 2020, a female was captured, giving the species one last chance for survival.

Now discover places around the world that have been taken over by animals