Sharks have been around for over 400 million years, and in that time, the vast majority of species that ever existed have gone extinct. The fossil record is filled with bizarre, massive, and surprisingly diverse sharks that disappeared long before humans arrived. Some vanished in mass extinction events, others lost out to changing oceans and new competitors. And today, a growing number of modern shark species are sliding toward the same fate.
The Earliest Sharks
The oldest shark-like teeth in the fossil record belong to an ancient fish called Doliodus problematicus, dating back roughly 410 million years to the Early Devonian period. By 380 million years ago, creatures like Antarctilamna had appeared, though they looked more like eels than anything you’d recognize as a shark.
Cladoselache evolved around the same time and is one of the first animals we’d actually call a shark. Fossils found in North America and Europe show it was built for speed: a streamlined body with broadly attached fins and a mouth that opened at the front of the skull rather than underneath it. It had two dorsal fins and strong defensive spines behind its head. Cladoselache disappeared by the end of the Devonian period, around 359 million years ago, likely as ocean conditions shifted and new predators emerged.
The Bizarre Sharks of the Carboniferous
The Carboniferous period, starting about 359 million years ago, produced some of the strangest shark-like creatures ever to exist. Many of these actually evolved from the chimaera lineage, a group related to but distinct from true sharks.
Stethacanthus had an anvil-shaped dorsal fin covered in tiny tooth-like structures, a feature so unusual that scientists still debate its purpose. Falcatus males sported a long spine that jutted from their backs and curved forward over their heads, possibly used in mating displays. And then there was Helicoprion, perhaps the most alien-looking of them all. Its lower jaw contained a spiral whorl of teeth that functioned like a circular saw. A 2014 study in the Journal of Morphology confirmed the whorl occupied the entire length of the lower jaw and worked as a multi-purpose feeding tool: front teeth hooked and dragged soft-bodied prey into the mouth, middle teeth pierced and sliced, and rear teeth pushed food deeper into the throat. Each tooth traced a curved slashing path during jaw closure, essentially sawing through prey with every bite. Helicoprion survived until around the end of the Permian, roughly 250 million years ago.
Cretaceous Apex Predators
Cretoxyrhina mantelli, nicknamed the “Ginsu shark,” was one of the most fearsome predators in the oceans between about 107 and 73 million years ago. Growing up to 7 meters (23 feet) long, it occupied the same waters as mosasaurs, plesiosaurs, and giant fish, and it ate all of them. Fossil evidence from the Niobrara Formation in Kansas shows bite marks and embedded teeth linking Cretoxyrhina to attacks on mosasaurs, plesiosaurs, large bony fish, and even pterosaurs, the flying reptiles that skimmed the sea surface. Scientists compare its ecological role to the largest modern lamnid sharks, like great whites, but it disappeared before the end of the Cretaceous, possibly outcompeted by mosasaurs that were diversifying during the same period.
Megalodon: The Largest Shark That Ever Lived
No list of extinct sharks is complete without Otodus megalodon. It evolved from Otodus obliquus, which appeared during the Palaeogene period (66 to 23 million years ago), and grew into the biggest predatory shark the world has ever seen. Previous estimates based on tooth size put its maximum length at 15 to 18 meters (49 to 59 feet). A 2025 study, authored by 29 fossil shark experts and based on nearly complete vertebral columns found in Belgium and Denmark, pushed that estimate to a possible 24.3 meters (about 80 feet).
Megalodon went extinct around 2.6 million years ago, right at the boundary between the Pliocene and Pleistocene epochs. A fossil record analysis published in PLOS ONE found that the most likely extinction window falls between 3.5 and 2.6 million years ago. The cause was almost certainly a combination of cooling oceans, shifting prey populations, and increased competition. As sea temperatures dropped, the warm coastal waters megalodon depended on for nursery habitat shrank. Meanwhile, smaller, more efficient predators like early great white sharks were on the rise.
Why Ancient Sharks Disappeared
Prehistoric shark extinctions generally align with major shifts in ocean chemistry, temperature, and oxygen levels. The Permian-Triassic extinction event around 252 million years ago, the most devastating mass extinction in Earth’s history, wiped out the majority of marine species including many shark lineages. The end-Cretaceous extinction 66 million years ago, triggered by an asteroid impact, eliminated another wave. Between these catastrophic events, slower changes in sea level, water temperature, and available prey drove countless species to extinction over millions of years. Sharks that were highly specialized, dependent on narrow temperature ranges or specific prey, were always the most vulnerable.
Modern Sharks on the Brink
No shark species has been officially declared globally extinct in modern times. But that statistic hides a grim reality: 28 populations of sharks, rays, and related species have already been wiped out at the regional or local level, according to a comprehensive review of IUCN data by researchers at the University of Miami. Sawfishes, skates, and angel sharks have been hit hardest, disappearing entirely from waters where they once thrived.
The Pondicherry shark is one of the most likely candidates for modern extinction. Once found across the Indo-West Pacific from the Gulf of Oman to New Guinea, it is now classified as critically endangered, and confirmed sightings have essentially stopped. Old records place it near river mouths and coastal shelves in India and Pakistan, but those reports remain unverified in recent decades.
Overfishing is the primary driver of modern shark decline. Targeted fisheries, bycatch in gillnets and longlines, and artisanal fishing have all contributed. Few of the species now considered threatened were in trouble as recently as 1980, but the rapid expansion of shark and ray fisheries changed that within a single generation. Climate change is compounding the problem. Rising sea temperatures are bleaching coral reefs that some species depend on for habitat, and shifting thermal zones are pushing sharks into narrower coastal areas where fishing pressure is even more intense. Off the southern coast of South Africa, for example, warming waters have forced multiple shark and ray species to shift their ranges northeastward into a much narrower stretch of continental shelf, concentrating them in areas with heavy fishing activity.
The Shorttail Nurse Shark illustrates both threats converging. Once classified as vulnerable, it has been uplisted to critically endangered after significant population declines over just 15 years, driven by overfishing and ongoing coral reef degradation from bleaching events and rising water temperatures.