There are so many reasons that animals go extinct, in more recent years it is generally due to human intervention. From building homes to devastating rainforests and other ecosystems with climate change, our animal kingdom shrinks by the year. Disease, epidemic, and even acid rain can inhibit animals from surviving, even cosmic radiation can come into play. Despite all of these factors the largest interference in the animal kingdom comes from climate heating and cooling as well as changes in currents or sea levels. Some extinction is a form of speciation, where an animal adjusts to ecological settings and evolves, leaving the former species to go extinct.
Lots of animals became extinct before humans even existed, like dinosaurs or giant sea predatory monsters. When the ice age came many of these enormous species died off, which is probably one reason that humans were able to survive enough to evolve where we’ve gotten to today. Biologists and ecologists study the past, present, and future trends that might affect the animal kingdom since human beings are, in fact, a part of it. More than 99% of all the 5 billion species that have ever existed are now extinct. These are some of the biggest, scariest, predatory ones that we could find.
About 34 to 40 million years ago the Basilosaurus was a gigantic whale, but when the fossil was discovered scientists thought that it was a reptile hence the suffix -saurus. Later the fossil, discovered in the United States, was found to be a marine mammal. Although Richard Owen tried to rename the whale Zeuglodon but according to taxonomic rules the first name stuck. This species is the state fossil of Mississippi and Alabama even though the first Basilosaurus fossils were found in Egypt and Jordan. Modern whales are said to be one of the most intelligent and social creatures in the ocean but the Basilosaurus is said to have a much smaller brain than their modern counterparts. An interesting makeup of the inner ear implies that the Basilosaurus can hear directionally underwater using acoustic isolation. The bite of the Basilosaurus exerted 16,400 to 20,000 pounds per square inch which is the strongest bite force of any organism including the T.Rex.
Dating back to the Cretaceous era in what we now call South America and Africa the Sarcosuchus lived 112 million years ago. The first discovery of this crocodilian animal was found by an expedition led by French paleontologist Albert-Félix de Lapparent in the Sahara Desert. In this expedition, which took place between 1946 to 1959, scientists found fragments of skull, teeth, scutes, and vertebrate. Measured at twice the length of a modern crocodile the Sarcosuchus weighed up to 8 tonnes. After the initial dig an entire skull was found in Niger by the French CEA in 1964. With all of this early data it still wasn’t until 1997 to 2000 that the anatomy became known to science. The Sarcosuchus had telescoped eyes and an extra long snout that made up about 75% the length of the skull. It is estimated to have measured around 11-12 m. The mouth of this creature contained 35 teeth on each side of the upper jaw and 31 teeth on each side of the lower jaw.
Fossils of this prehistoric genus of sea turtle has been found in South America embedded in rock dating back 5 to 6 million years. The exceptionally wide sea animal measured almost six feet long and is called the largest turtle that has even existed. Currently the largest freshwater turtle that exists is the Arrau turtle which lives in the Neotropics. Though this is the most closely related turtle in the world the Arrau turtle only measures about 30 inches. Two species of Stupendemys have been discovered as of right now: the Stupendemysgeographicus and the Stupendemyssouzai. The size and location vary between each species. The immense weight of the Stupendemys helped the giant sea turtle remain underwater to graze on aquatic plants, this was important because the Stupendemys was thought to be a very weak swimmer. As a result, Stupendemys probably avoided swift currents and smaller streams because it could not swim against even the smallest current.
This now extinct sea scorpion was said to have lived almost 400 million years ago and measured in over 8 feet, a horrifying length that is larger than almost every human alive. The Jaekelopterus is the largest arthropod that has ever been discovered and has been found in two species. Jaekelopterusrhenaniae was discovered in freshwater strata in Rhineland, the claw of which was first discovered near Prum in Germany. It was discovered that the Jaekelopterus spent time in freshwater lakes and rivers, most likely never venturing into the ocean. In the lake & stream environment, the Jaekelopterus was probably the top predator in its environment snacking on fish and even other arthropods. Arthropods include crabs, insects, and spiders, all animals that are now extremely small. This was what made the discovery of this arthropod was so exciting for the scientific community.
Over 300 million years ago in the Carboniferous era of the Earth the Arthropleura was native to what we now refer to as North Eastern Scotland and North America. The extinct millipede arthropod would grow anywhere between one and seven and a half feet and by theory could have very few predators because in this genus are the largest known land invertebrates of all time. Though many believe that the Arthropleura was a predator, others say that the Arthropleura was a plant grazing herbivore. The reason that this isn’t factual just yet is because it has been hard to find a fossil that prominently displays the mouth, but some recent discoveries show that the Arthropleura had very weak mouth muscles. However, other discoveries have shown lycopods within the stomach cavity of the Arthropleura showing that some of them had evolved to a predatory mindset. Their tracks show a quick moving millipede and are called Diplichnitescuithensis.
10. Argentavis Magnificens
Translated this literally means “magnificent Argentine bird” or “magnificent silver bird” because it was once one of the largest flying birds to have ever existed. The bird is also called the giant teratorn and it dates back to the late Miocene era and is said to have existed in three sites around Argentina as a good deal of fossils were found in these locations. The estimated wingspan of the Argentavis magnificens is anywhere from 16 to 20 feet depending on the scaling done by the paleontological team. The height of the giant teratorn is estimated around 4.9 to 6.6 feet, the largest flying bird until a 2014 discovery. Scientists have spent much time tracking extant birds to figure out more about the Argentavis magnificens which has led them to accept many facts, like the fact that something this huge can fly in the first place. It is also widely believed that the Argentavis magnificens laid 1-2 eggs every two years.
9. Dromornis Stirtoni
These extinct land birds are believed to have looked much like emus, but giant. At almost ten feet tall the Dromornisstirtoni had a long neck and stub-like wings which explain why it was flightless. Though it is believed that its legs were powerful the Dromornisstirtoni wasn’t a fast runner. It had a large, strong, prominent beak and scientists often argue whether the beak was strong because the bird was a carnivore or if it was to help the bird eat tall, strong stalks of plants. The Dromornisstirtoni inhabited subtropical open woodlands in Australia in the late Miocene and early Pliocene eras. These giant birds were believed to live anywhere from 8 million to 30,000 years ago since the animals of Australia evolved very slowly almost completely isolated from animals on other continents. The first sign of this emu-like bird was found in 1872 in Peak Downs, Queensland before being described by Richard Owen.
8. Josephoartigasia Monesi
As the largest rodent known to man estimated to grow to about 10 feet long, the Josephoartigasiamonesi terrifies almost any sane human being. The South American caviomorph rodent has been extinct for anywhere from two to four million years, they existed during the Pliocene to the early Pleistocene eras. The Josephoartigasiamonesi is also sometimes called the giant pacarana, a name that refers to the closest living relative of the extinct rodent. The skull alone is said to have been 21 cm long with a 12-inch incisor. This gigantic tooth is said to have been used in violent mating rituals while fighting for their mates. It is also possible that the giant pacarana defended itself and its family against giant predators at the time which included marsupials, saber-toothed cats, short-faced bears, and terror birds. The rodent most likely lived in an estuarine environment eating soft vegetation like fruits and plants.
Translated this species name means “Shandong Lizard” because it was found in the Cretaceous Wangshi Group of Shandon Peninsula in China. The genus of saurophinehadrosaurid dinosaur is the absolute largest hadrosaurid taxon in the world with a femur measuring 1.7m. This is one of the largest known ornithischians with a five-foot skull and a composite skeleton which is actually mounted at the Geological Institute of China in Beijing. That skeleton is about 48 feet in length and guessed to weigh as much as 18 short tons. The beak of the Shantungosaurus was toothless but its jaw was packed with around 1500 sharp, tiny little teeth. There was also a large hole near the nostrils of the dinosaur that is theorized to have been covered with a flap that was inflated to make sounds. Theories on the Shantungosaurus are made from five incomplete skeletons of different dinosaurs, it was first discovered and documented in 1973.
Most closely related to modern-day dragonflies the Meganeura is an extinct insect from the Carboniferous period which ended about 300 million years ago. In 1880 the first Meganeura fossils were discovered in the French Stephanian Coal Measures of Commentry. Five years later French paleontologist Charles Brogniart described that fossil and named it Meganeura which means “large-nerved”. This moniker is a reference to the large network of veins on the wings of the giant insect. Another fossil was found in 1979 at Bolsover in Derbyshire, it is this specimen of Meganeura that is housed at the Muséum national d’histoirenaturelle, Paris. The reasoning behind the enormity of the Meganeura is a controversial argument in Paleontology. One theory is that the lack of predators allowed the Meganeura to grow immensely, another theory is that the air density at that time had much more concentrated oxygen which allowed the insect to grow. The last theory is that the Meganeura began its life underwater and then evolved above water, the growth was a way for the animal to adjust to the much higher levels of oxygen.
The Spinosaurus, or “spine lizard” is a genus of theropod dinosaur that derives from what we now know as North Africa about 112 to 97 million years ago. The fossil of this genus was first discovered in 1912 in Egypt and described three years later by German Paleontologist Ernst Stromer, these remains were unfortunately destroyed in World War II. Though lots of evidence has been compromised the Spinosaurus is said to be bigger than the Tyrannosaurus and the Giganotosaurus. In 2005, 2007, and 2008 reports were published that suggested the Spinosaurus was anywhere from 41-59 feet and weighed anywhere from 7.7 to 23 short tons. Since then a complete specimen has been recovered and in 2014 more research was released that the Spinosaurus was similar in build to a modern crocodile and could grow larger than 49 feet. The animal also featured a ‘sail’ on its back that contained vertebrate that reached over ten times larger than the natural body of the lizard.
4. Pliosaurus Funkei
Two partial skeletons that were found in Norway south of Sassenfjorden are housed at the University of Oslo Natural History Museum. These skeletons were found on the southeast side of Mount Knerten in the Arctic Spitsbergen island 2m apart from one another. This excavation lasted eight years and many other reptiles and fossils were discovered during this time. Originally the giant sea monster was named ‘Predator X’ until given the official name Pliosaurus funkei. It has four fins, most believe that the first two fins are used to cruise through the water and the back two were used to pick up speed or chase prey. The bite of this enormous animal is theorized to be stronger than that of the ultimate predatory dinosaur the Tyrannosaurus Rex. The skull would be somewhere between six and eight feet long for a larger specimen. Body lengths were estimated around 33 and 42 feet.
3. Arctodus Simus
Most commonly this extinct species is called the short-faced bear, it existed in North America during the Pleistocene epoch. This species of short-faced bear, of which there are two, is said to be the largest terrestrial mammal carnivores that ever existed. They are said to have died off during the global cooling in 10,900 BC, this is called the Younger Dryas period. Their name comes from their prominently smaller snout than other common bears which are a trait shared by a distant relative to Arctodussimus, the spectacle bear. The fun fact of the matter is that the shortness of the bear’s snout is only an optical illusion caused by their short nasal region and deep snout. This species first appeared in North America 800,000 years ago from Mississippi to Alaska, it became extinct about 11,600 years ago. Some fossils were found in a cave in Shasta County, California but the only skeleton found was excavated in Indiana.
This giant extinct snake measured out around 32 feet which at one time was the largest known snake. Gigantophis lived in the Northern Sahara about 40 million years ago and was learned about from a small series of fossils. The first discovery regarding Gigantophis was in 1901 and was named in honor of Sir William Gastini, KCMG, the Under Secretary of State for Public Works in Egypt. The paleontologist that discovered the first Gigantophis fossil was Charles William Andrews. These fossils were studied more recently at the Smithsonian Institute in Washington, D.C. and Jason Head deduced from the vertebrate that the snake could grow anywhere from 30.5 to 35.1 feet. This would make it 10% larger than all other known snakes. Gigantophis was replaced as the largest snake in the world by Titanoboa, a truly terrifying prehistoric snake. Most commonly the gigantic snake would resemble an enormous python.
1. Titanoboa Cerrejonensis
Until 2009 the world thought that the Gigantophis was the largest known snake, but that was before Titanoboa was discovered. The extinct genus of the snake was said to have lived 60-58 million years ago in the Paleocene Epoch. Like most fossils scientists debate on why the Titanoboa is so large. Some say it is because the climate in the region where it was found was much warmer when it was alive but some scientists disagree with this. The fossils were excavated the Cerrejon Formation of the coal mines of Cerrejon in La Guajira, Colombia. Comparing the sizes and shapes of the vertebrate fossils with those of extant snakes scientists believe that Titanoboa could grow up to 42 feet long. In a promotion for a television show Titanoboa: Monster Snake on the Smithsonian Channel a full-scale replica of Titanoboa was displayed in Grand Central Terminal in New York City.