Buzz
Millions of years ago, some of the largest and most intimidating creatures ever to roam the Earth prowled the seas. Here are ten of the most monstrous sea predators that terrorized the oceans:
10. Shastasaurus
Ichthyosaurs were ocean-dwelling hunters resembling today's dolphins, but they could grow to enormous sizes during the Triassic period, over 200 million years ago.
Shastasaurus, the largest marine reptile ever discovered, was a type of ichthyosaur that could grow up to 65 feet (20m), far exceeding the size of most other sea predators. Despite its enormous size, Shastasaurus wasn't a fierce hunter; it was a specialized suction feeder, mainly consuming fish.
9. Dakosaurus
Dakosaurus was first uncovered in Germany and, with its strange blend of reptilian and fish-like features, became one of the top sea predators of the Jurassic period.
Fossil evidence has been found all over the world, from England to Russia to Argentina. Often compared to modern crocodiles, Dakosaurus could reach lengths of 16 feet (5m). Its distinct teeth have made scientists classify it as an apex predator during its reign.
8. Thalassomedon
Thalassomedon was a Pliosaur species whose name, derived from Greek, means 'sea lord'—a fitting title for such a formidable predator. These giant creatures could grow to lengths of up to 40 feet (12m).
Its flippers, measuring nearly 7 feet (2m) in length, allowed it to navigate the ocean depths with lethal precision. This apex predator dominated the seas throughout the late Cretaceous period, eventually being overshadowed by the emergence of even larger hunters like the Mosasaur.
7. Nothosaurus
Nothosaurus, measuring about 13 feet (4m) in length, were formidable and aggressive hunters. Their mouths were filled with sharp, outward-facing teeth, indicating they likely fed on squid and fish. Nothosaurus is believed to have been an ambush predator, utilizing its streamlined, reptilian body to quietly approach its prey and strike unexpectedly.
It is thought that Nothosaurs shared a close evolutionary link with pliosaurs, another group of deep-sea hunters. Fossil evidence shows that they lived during the Triassic period over 200 million years ago.
6. Tylosaurus
Tylosaurus was a massive species of Mosasaur, reaching lengths of over 50 feet (15m), making it an overwhelming presence in the ocean.
The Tylosaurus was a carnivorous predator with an incredibly varied diet. Stomach contents reveal it ate fish, sharks, smaller mosasaurs, plesiosaurs, and even some flightless birds. These creatures thrived during the Late Cretaceous period in the seas that once covered North America, where they reigned as the top predators for millions of years.
5. Thalattoarchon Saurophagis
T. saurophagis, discovered only recently, was the size of a school bus, measuring nearly 30 feet (9m) long. This early ichthyosaur lived during the Triassic period, about 244 million years ago. Its existence, shortly after the Permian extinction (the largest mass extinction on Earth, when 95% of marine life was wiped out), provides valuable insights into the rapid recovery of ecosystems.
4. Helicoprion
Who wouldn’t be terrified by the nightmarish jaw of Helicoprion, a giant, 270-million-year-old cartilaginous fish with a unique spiral arrangement of teeth in the center of its mouth? Closely related to sharks, this sea creature was first discovered in 1899, but scientists were puzzled by the strange shape and function of its jaw.
Recent research has revealed that Helicoprion had a concealed tooth production system that started where the upper and lower jaws met, extended over the area where the tongue would be if it had one, and continued into the cartilage supporting the lower jaw. Fossilized teeth have shown that these creatures grew to lengths of at least 25 feet (about 8m).
3. Megalodon
One of the largest predators in marine history, and the largest shark ever recorded, Megalodons were as fearsome as they come.
Megalodons roamed the oceans during the Cenozoic Era, between 28 and 1.5 million years ago. These monstrous sharks were a much larger version of today’s great white, an apex predator in today’s seas. While modern great whites can reach up to 20 feet (6m), Megalodons could grow to a staggering 65 feet (20m)—longer than a school bus!
2. Mosasaurus
If the Liopleurodon was massive, then Mosasaurus was truly gigantic.
Fossil evidence indicates that Mosasaurus could grow up to 50 feet (15m) in length, making it one of the largest marine predators of the Cretaceous period. With a head resembling that of a crocodile and lined with hundreds of razor-sharp teeth, Mosasaurus was capable of killing even the most heavily armored foes.
1. Liopleurodon
Liopleurodon was a marine reptile that grew to more than 20 feet (6m) in length. It primarily inhabited the seas that covered Europe during the Jurassic period and was one of the era's dominant predators. Its jaws alone are estimated to have exceeded 10 feet in length—about the distance from the floor to the ceiling.
With teeth of that size, it’s no surprise that Liopleurodon ruled the food chain.
