The Acanthodian shark was considered a transitional species between sharks and bony fish like tuna. These creatures were one of the first animals to have a jaw, and just like modern sharks, they had a skeleton made entirely of cartilage. Its fins were supported by bony spines, like the modern-day ray-finned fish.
Known as “spiny sharks,” they rarely grew more prominent than 30 centimeters, but since they lived more than 360 million years ago, they were still considered one of the largest filter-feeding animals of its time. Filter feeders trap food particles through their gills.
Known as the “hooked-tooth mako,” the Isurus planus lived during the Micoene epoch between five and 23 million years ago. These underwater predators fed mostly upon fish, pinnipeds, and small whales that came their way.
The description of the Isurus planus comes mostly from its teeth, which are sharp and slightly curved. The sharks were about 20 feet in size, and their fossils have been found in Australia, Japan, and California. The mako shark is the closest living relatives to the Isurus planus.
The Scapanorhynchus shark is considered a “spade snout” fish that lived in the early Cretaceous era to the Miosene between 145 to 5.3 million years ago. This type of shark shares many similarities with the modern goblin sharks, which are the closest living relative.
These sharks reached lengths of up to 10 feet long. The most prominent feature was its snout, which was not only elongated but equipped with sharp teeth used for catching fish and other prey. The fossils of the Scapanorhynchus have been found in various areas around the Atlantic Ocean.
The long-snouted Bandringa shark was considered an early close relative of modern-day sharks. They resembled sawfish and paddlefish and were known for their spoon-billed snout, which covered half of its body length. Juveniles were about six inches long, while the adults could grow up to 10 feet in length.
They were discovered in 1969, and scientists used to believe that the genus only lived in freshwater swamps and rivers while a second classification dwelled in shallow oceans. In 2014, researchers evaluated fossils and found that the Bandringa species had also lived in saltwater.
The broad-toothed mako, or Cosmopolitodus hastalis, was a species of mackerel shark that lived 2.5 to 23 million years ago between the Miocene and Pliocene epochs. The relatively large sharks were apex predators that grew to about 13 feet long.
Scientists have pondered if some species grew larger, based on the size of the 3.5 inch long teeth. The teeth are big and triangular in size. The apex predators had a traditional mako shark form, and they looked similar to the modern great white sharks.
The Carcharocles angustidens were a mega-toothed shark species. They lived during the Oligocene and Miocene epochs between 33 and 22 million years ago. While there have not been many fossils found of this species outside teeth, experts suggest that the sharks were more massive than today’s great white shark and had similar morphological traits.
The sharks were thought to be 31 feet long, and the teeth are nearly four inches in diagonal length. The fossils have been found in New Zealand, North America, Europe, Asia, Africa, and South America. The Carcharocles angustidens have no extant relatives, but they are related to the megalodon.
Hybodus sharks were known as “humped tooth” sharks, coming from the genus that existed during the Permian period. They disappeared during the Late Cretaceous, between 290 and 66 million years ago. The sharks had a traditional streamlined body with two dorsal fins.
The sharks had two types of teeth, which likely helped them catch and eat faster prey, like shellfish and other sea critters. Hybodus were more than six and a half feet long, and scientists believe that these sharks preferred to swim in shallow seas all over the world. The abundant amount of fossils suggests that hybodus were successful predators. It is unsure of why the genus became extinct.
The Ginsu shark, or Cretoxyrhina, was a mackerel shark that lived during the Late Albian to Campanian of the Late Cretaceous period, more than 100 to 84 million years ago. The sharks looked similar to the modern great white shark, even though the two species are not related.
This apex predator were one of the top of the Cretaceous seas. They fed on mosasaurs and plesiosaurs. One specimen was even found to have undigested remains of a giant Cretaceous fish. The Cretoxyrhina sharks were more than 23 feet long, and they swam in the Cenomanian-Campanian seas all across the world.
The Ptychodus sharks were part of the genus of hybondontiform and durophagous sharks that populated during the Late Cretaceous era. Experts estimate that they died more than 85 million years ago.
Also known as crusher sharks, these sharks were known for their plate teeth and their dietary preferences of mollusks, shellfish, invertebrates, carrion, and other sea creatures. These sharks crushed the shells of their prey while they were eating. The sharks were 33 feet long, and their fossils had been primarily located in the Western Interior Sea. They are considered to be the most enormous shellfish-eating creatures ever.
This kind of freshwater shark lived from the later Devonian period until the end of the Triassic. Scientists estimate that the sharks disappeared from the fossil record more than 202 million years ago. The Xenacanthus is often referred to as the “eel shark” because it has an elongated dorsal fin that extends along the spine.
These sharks were small, only three feet in length. The dorsal fin was ribbon-like, and it ran the entire length of the body to the tail, where an anal fin joined it. The closest living relatives are the stingray and other sea-dwelling species.
Another extinct freshwater shark, the Orthacanthus, lived in swamps and bayous approximately 225 million years ago. Scientists have also found fossils dated back to the Denovian era more than 400 million years ago. These sharks had long spines that extended from the back of the skull to the end of the body.
The Orthacanthus sharks were about 10 feet in length, and they looked more like a giant eel. The sharks were found in Europe and North America. Experts believe the sharks could have been cannibalistic because developing teeth were often found in the coprolites of adults.
The Anisopleurodontis was a genus of shark that was known to only one species. The sharks were closer concerning modern chimaeras than sharks, and they lived during the Permian era approximately 300 million years ago.
While not much has been uncovered about these sharks, the creatures were almost 10 feet in length, and they had an enlarged heart. The fossils have been found in the Parnaiba Basin of South America.
The Helicoprion is mostly known for its unique mouth. A cartilaginous structure helped the shark develop a strange tooth structure. Scientists believe that it lived during the Permian age approximately 290 million years ago.
The spirally-arranged cluster of teeth was known as “tooth whorls,” and the structures measure up to 18 inches in length. Experts believe these sharks were quite large and could grow up to 39 feet long. The fossils have been found in China, Australia, the Ural Mountains, and North America.
The Edestus shark swam the oceans during the Late Devonian to Late Carboniferous more than 300 million years ago. These sharks grew teeth in curved brackets, and they would not shed their teeth as they became worn like today’s sharks. There was only a single row of teeth on each jaw, and the sharp and serrated teeth were like scissoring shears.
These sharks are believed to have swum in all of the world’s oceans during their time on earth. While there are no extant relatives, the helicoprion is believed to be a relative to the Edestus.
The Stethacanthus was a part of the shark-like genus Holocephalian, a primitive form of fish and early modern shark ancestor. These creatures lived between the Late Denovian period to the Early Carboniferous epoch, between 420 and 324 million years ago.
Also known as the anvil shark, the Stethacanthus had a dorsal fin that was shaped like the tool. It also had small spikes that protruded through the top. The peaks continued along the top of its head, which were formed from its scales. These relatively small creatures were approximately 2.3 feet long, and the fossils have been found in Asia, Europe, and North America. The Stethacanthus are more closely related to chimaeras, like the ratfish, spookfish, and ghost shark.
The Cladoselache were living in the ocean during the Denovian period more than 400 million years ago. This species was known as one of the oldest known sharks with a nearly fully preserved fossil. It swam in oceans of what is now considered North America.
This shark is considered by scientists to be the first “true” shark. The sharks were covered in scales, and it had a small patch along the edges of its fins. They were about 5.9 feet in length, and they had little mouths and smooth-edged teeth, which were suited for grasping, tearing, and chewing.
The McMurdodus is considered the earliest known modern shark, which lived in the middle of the Devonian period about 390 million years ago. The classification is based on the tooth enamelooid, meaning it is more closely related to modern sharks than other extinct species.
These sharks were thought to be between 4.6 and 18 feet long. Most of their fossils have been found in Western Queensland, Australia. The closest living relative is believed to be the cowshark; however, scientists say there is nearly a 200 million year gap in the fossil record between these two species.
The Cretolamna shark existed during the Cretaceous and Paleogene periods, which was approximately 50 to 90 million years ago. Fossil records have been found in the waters of North America, Africa, and the Middle East.
Although not one of the biggest prehistoric sharks, the Cretolamna still had an impressing length of about nine feet long. They preyed mostly upon sizeable bony fish, turtles, squids, mosasaurs, and other sharks.
The Cobelodus shark looked very different in comparison to today’s modern sharks. They had round heads and an arched back. The single dorsal fin was located at the end of the back. The sharks came from the Symmorlida family.
Scientists have nicknamed the shark the Godzilla shark because its teeth resembled its namesake. This prehistoric species lived in North America during the Carboniferous period. They were about seven to nine feet in length.
The Carboniferous Period was about 360 to 286 million years ago, and scientists have dubbed the era like the Golden Age of Sharks because shark diversity flourished. By the end of the period, there were approximately 45 families of sharks!
The Falcatus falcatus were tiny but mighty; scientists estimated that the sharks were six inches in length. One preserved fossil even depicts a couple of the sharks mating, with the larger female grabbing the male by its head spine!
The Elegestolepis is shrouded in much mystery. Scientists only know what they could gleam from fossilized placoid scales. It is believed that the sharks were covered in placoid scales that were hydro dynamically shaped to keep down water resistance.
These sharks were believed to have lived in the late Silurian period, more than 420 million years ago. They are thought to be one of the earliest sharks, even predating much of the life on land.
The borneo shark was once thought to have been extinct. The scarce species was discovered in 2004. The small gray shark is only 26 inches in length. The slender body includes a long pointed snout and a second dorsal fin behind its anal fin. The sharks mostly feed on bony fishes.
It is the only member of its genus to have a row of enlarged pores above the corners of its mouth. Before its sighting, the last recorded time a Borneo shark was spotted was in 1937. The shark continues to gain conservation concern from scientists.
Previously known as the false smalltail shark, the Carcharhinus obsolerus has not been seen in more than 80 years, and scientists believe they may have become extinct. The species was known to swim in the Western Central Pacific Ocean area, and the last three specimens found were in Borneo, Vietnam, and Thailand.
Although they have not been seen since 1937, scientists are hopeful that the lost sharks are not entirely lost. The rediscovery of the borneo sharks gives them hope that these sharks could be found again.