Animals Wildlife 16 Animals That Are Living Fossils These animals' bizarre, eccentric traits make them seem almost like aliens. By Bryan Nelson Bryan Nelson Twitter Writer SUNY Oswego University of Houston Bryan Nelson is a science writer and award-winning documentary filmmaker with over a decade of experience covering technology, astronomy, medicine, animals, and more. Learn about our editorial process Updated May 5, 2022 Jacek Fulawka / Shutterstock Share Twitter Pinterest Email Animals Wildlife Pets Animal Rights Endangered Species A living fossil is an organism that has retained the same form over millions of years, has few or no living relatives, and represents a sole surviving lineage from an epoch long past. Many living fossils alive today, like the pig-nosed turtle and the goblin shark, have unusual traits that make them seem otherworldly. They have often survived several mass extinctions, and many scientists consider them to be a rare glimpse into how life on Earth was long ago. Here are some examples of these amazing creatures. 1 of 16 Komodo Dragon GUDKOV ANDREY / Shutterstock Most people would agree that no other lizard in the world looks more prehistoric than a komodo dragon. They can be traced to the genus Varanus, which dates back about 40 million years. They are the largest and heaviest lizards in the world, measuring as long as 10 feet and weighting up to 350 pounds. They are the dominant predators in their habitat, eating almost anything they find. Sometimes they'll consume up to 80% of their body weight in a single feeding. While they are famously named after the Indonesian island of Komodo, their ancestors first appeared in Australia, some 100 million years ago. 12 Surprising Facts About Komodo Dragons 2 of 16 Sandhill Crane Haricharan / Flickr / CC BY-ND 2.0 While many birds can trace their ancestry back to dinosaurs, fossils show that the sandhill crane itself dates back 10 million years. Three species of sandhill cranes are migratory and three are non-migratory. Two of the non-migratory species—the Cuban sandhill crane and the Mississippi sandhill crane—are critically endangered. Sandhill cranes are popular with bird enthusiasts because of the annual migration of several species. Hundreds of thousands migrate from Mexico and the southern United States all the way up to the Arctic. 3 of 16 Aardvark Kelsey Green / Shutterstock Aardvarks are nocturnal, burrowing animals and are the only living species in the order Tubulidentata. Genetically, the animal can be considered a living fossil because of the ancient arrangement of its chromosomes. Also, its teeth are unlike any other mammals', appearing like clusters of hundreds of straws standing upright. These little tubes are constantly being worn down and regrown. Aardvark fossils dating back 5 million years have been found in South Africa. Aardvarks are part of the group of animals that includes elephants, hyenas, and golden moles. 4 of 16 Red Panda Hung Chung Chih / Shutterstock Hailing from the temperate forests of the Himalayas and the mountains of China, these adorable creatures are the only surviving members of the family Ailuridae. They have no living relatives and their nearest fossil relative, Parailurus, lived 3 to 4 million years ago. In 2020, scientists discovered that there are two distinct species of red pandas: the Himalayan red panda and the Chinese red panda. Relatives of the red panda lived between 5 and 12 million years ago. Despite their shared taste for bamboo, red pandas are not closely related to giant pandas. 15 Remarkable Red Panda Facts 5 of 16 Tuatara BeautifulBlossoms / Shutterstock They may look like lizards, but tuataras are actually part of a different order called Sphenodontia. Only two species of tuatara exist today, and they have much the same form as their ancient ancestors that thrived 200 million years ago. There are tuataras alive today that are well over 100 years old, and some experts believe they could live to be more than 200 years old under the right conditions. These amazing, long living creatures can only be found only on small islands off the coast of New Zealand. Unlike lizards, they enjoy cooler temperatures and are nocturnal. 6 of 16 Nautilus kikujungboy CC / Shutterstock The nautilus represents the only living member of the subclass Nautiloidea. Nautiluses are cephalopods that retain an outer shell unlike other distantly related animals such as squid and octopus. Their beautiful shells have inspired many artists over the centuries, and they are also among the finest natural examples of a logarithmic spiral or the golden ratio. Because of their long-lasting shells, the fossils of nautiluses are easier to come by than remains of other cephalopods, and fossil hunters have discovered ancient shells dating back at least 500 million years. 7 of 16 Purple Frog David V. Raju / Wikimedia Commons / CC BY-SA 4.0 Discovered as recently as 2003, this living fossil is also known as the pig-nosed frog due to its shapely snout. A rare burrowing species, the purple frog is difficult to find as it is only observed out in the open for short periods of time. Though found in India, the purple frog’s closest living relatives can only be observed on the Seychelles Islands, meaning these frogs have been around for approximately 120 million years dating back to when India, Madagascar, and Seychelles were connected as a single land mass. Purple frogs are listed as endangered and their population is decreasing. 8 of 16 Platypus worldswildlifewonders / Shutterstock With a snout like a duck and a hairy body like a mammal, it’s hard to find a more unique animal than the egg-laying platypus. They have 10 sex chromosomes instead of two (X and Y) like most other mammals, and are one of the most venomous mammals in the world. It's no surprise that they are the sole living representative of the family Ornithorhynchidae. Fossils of platypus-like mammals date as far back as 100 to 146 million years ago, making them extremely valuable for studying mammalian evolution. 9 Quirky Facts About the Platypus 9 of 16 Hagfish NOAA / Wikimedia Commons / Public Domain These animals may look like slimy eels, but many experts don't consider them to be fish. In fact, some taxonomists are hesitant to consider them vertebrates, since they are the only living animals that have a skull but not a vertebral column. From an evolutionary point of view, they can be recognized from fossils that date back to 330 million years ago, and they represent a crucial living link between vertebrates and invertebrates. One descriptor that is not a misnomer is slimy. In fact, hagfish secrete a gooey slime when handled or threatened, which in the wild helps them to escape from predators. The slime is a wondrous substance that expands by an astonishing 10,000 times within a half-second of release. 10 of 16 Hoatzin Corine06 / Flickr / CC BY-SA 2.0 These odd-looking, pheasant-sized birds are arguably the most debated living birds because their evolutionary tree is missing so many branches. The hoatzin is the only member of its family (Opisthocomidae), though some taxonomists also place them in their own order. They retain some characteristics that are not found in any other birds. For instance, as chicks they still retain claws on the ends of their wings, which aid them in climbing and clinging to trees. Evaluation of fossils suggests that hoatzin may have existed as far back as 34 million years ago. Regardless of how they fit into the evolutionary picture, they are stunning ancient animals found in the Amazon and Orinoco basins of South America. 11 of 16 Koala Weili Li / Getty Images These Australian marsupials are an icon for wildlife across the globe, with a familiarity that overshadows their uniqueness. Though often referred to as bears, they are not related to bears at all. In fact, they are members of the family Phascolarctidae. Their closest relative in the marsupial family is the wombat, but the species diverged at least 30 million years ago. As marsupials, they carry their young in a pouch. Fossils of koalas are rare, but these marsupials have likely been around for at least 30 to 40 million years. 9 Things You Didn't Know About Koalas 12 of 16 Pig-nosed Turtle pitcharee / Shutterstock As the only living member of the family Carettochelyidae, the pig-nosed turtle is one of a kind—and not just because of its distinctive snout. Unlike most freshwater turtles, these guys have flippers that more closely resemble those of marine turtles, making them almost entirely aquatic. This unique turtle, which was around over 140 million years ago, currently occupies a small area of southern Australia and northern New Guinea. 13 of 16 Horseshoe Crab Jarous / Shutterstock Despite their name, horseshoe crabs are not crabs at all. In fact, they aren't even crustaceans, being more closely related to arachnids like spiders than to anything else. But for years, there was doubt about their relationship to arachnids. In 2019, a team of evolutionary biologists from the University of Wisconsin-Madison analyzed a collection of genetic data and confirmed that horseshoe crabs are in fact related to arachnids. Horseshoe crabs have been around for about 450 million years. They are truly alien-looking—they even have blue blood. Horseshoe crabs also have a unique immune system, and studying them has led to breakthroughs in cancer research and spinal meningitis treatments. 14 of 16 Goblin Shark Dianne Bray / Museum Victoria / Wikimedia Commons / CC BY 3.0 au The frightening looking goblin shark is an ancient deep sea shark thought to be closely related to the extinct shark genus Scapanorhynchus, which existed as long as 66 million years ago. These sharks, which are known for their unusually long snouts, can grow to over 12 feet in length, but are rarely seen outside of their deep underwater habitat, usually off the coast of Japan. Goblin sharks are part of the Lamniformes order of mackerel sharks, which also includes basking sharks and great white sharks. 15 of 16 Elephant Shrew trabantos / Shutterstock Their common name suggests otherwise, but these odd-nosed animals are not related to shrews. Elephant shrews share a relationship to other distant and distinct animals such as aardvarks, elephants, and even manatees. Believed to exist as long as 45 million years ago, the elephant shrew gets its name from its long movable snout that's similar to a trunk. A 2020 observation of the Somali elephant-shrew in Africa has encouraged researchers who thought the species may have been lost. They are insectivores that release a strong musk from the underside of their tails as they move along and mark their territory. 16 of 16 Crocodiles Nneka Mckay / EyeEm / Getty Images No other animal deserves the title of living dinosaur like the crocodile. These beasts have exhibited the same body form since dinosaurs walked the Earth, surviving the mass extinctions that wiped out nearly all of their mammoth brethren. Crocodiles are also the closest living relatives of birds, representing a long-diverged connection between birds and reptiles. A common ancestor of both species existed over 240 million years ago. Some evidence suggests that crocodiles swam from Africa to South America, aided by ocean currents. View Article Sources "Komodo Dragon | San Diego Zoo Animals & Plants". Animals.Sandiegozoo.Org. "Creature Feature: The Tall, Bulky And Elegant Sandhill Crane". Forest Preserve District Of Will County. "Sandhill Crane | National Wildlife Federation". National Wildlife Federation. "Montbrook Sister Sites". Florida Museum. "Orycteropus Afer (Aardvark)". Animal Diversity Web. "Red Panda". Smithsonian's National Zoo. "Red Panda." 2007 Schools Wikipedia Selection. A Tale Of Two Pandas. University Of Utah Genetics Science Learning Center, 2018. "Tuatara". Doc.Govt.Nz. "Tuatara (Sphenodon Punctatus) Longevity, Ageing, And Life History". Genomics.Senescence.Info. "Tuatara." San Diego Zoo Wildlife Alliance. "4 Things To Know About The Nautilus - Ocean Conservancy". Ocean Conservancy. "The Enigmatic Purple Frog". Zoological Society Of London (ZSL). "IUCN Red List Of Threatened Species: Nasikabatrachus Sahyadrensis". IUCN Red List Of Threatened Species. Martin, Hilary C et al. "Insights Into Platypus Population Structure And History From Whole-Genome Sequencing". Molecular Biology And Evolution, vol 35, no. 5, 2018, pp. 1238-1252. Oxford University Press (OUP), doi:10.1093/molbev/msy041 "Evolution & Names". Australian Platypus Conservancy. "Eptatretus Stoutii (California Hagfish)". Animal Diversity Web. Yong, Ed. "No One Is Prepared for Hagfish Slime." The Atlantic. "Opisthocomus Hoazin (Hoatzin)". Animal Diversity Web. Mayr, Gerald, and Vanesa L. De Pietri. "Earliest And First Northern Hemispheric Hoatzin Fossils Substantiate Old World Origin Of A ‘Neotropic Endemic’". Naturwissenschaften, vol 101, no. 2, 2014, pp. 143-148. Springer Science And Business Media LLC, doi:10.1007/s00114-014-1144-8 "Phascolarctos Cinereus (Koala)". Animal Diversity Web. "Carettochelys Insculpta (Pig-Nosed Turtle, Pitted-Shelled Turtle, Warrajan)". Animal Diversity Web. "Pig-Nosed Turtle - EDGE Of Existence". EDGE Of Existence. "Facts About Horseshoe Crabs And FAQ". Myfwc.Com. Ballesteros, Jesús A, and Prashant P Sharma. "A Critical Appraisal Of The Placement Of Xiphosura (Chelicerata) With Account Of Known Sources Of Phylogenetic Error". Systematic Biology, vol 68, no. 6, 2019, pp. 896-917. Oxford University Press (OUP), doi:10.1093/sysbio/syz011 "Mitsukurina Owstoni (Elfin Shark)". Animal Diversity Web. "Sharks". Smithsonian Ocean. "Did You Know The Elephant Shrew Is More Closely Related To An Elephant Rather Than A Shrew?". African Wildlife Foundation. "Tiny Elephant Shrew Resurfaces After More Than 50 Years On Lost Species List". Npr.Org, 2020. Heritage, Steven et al. "New Records Of A Lost Species And A Geographic Range Expansion For Sengis In The Horn Of Africa". Peerj, vol 8, 2020, p. e9652. Peerj, doi:10.7717/peerj.9652 "Scientists Reconstruct Genome Of Common Ancestor Of Crocodiles, Birds, Dinosaurs". Engineering.Ucsc.Edu, 2014. Machemer, Theresa. "New Evidence Suggests Ancient Crocodiles Swam from Africa to America." Smithsonian Magazine.