The prehistoric oceans were filled with some of the most terrifying and gigantic creatures that have ever existed. These sea monsters, which populated the depths of the ancient seas, were larger, more frightening, and stranger than anything we find in our oceans today. Here is a description of the first five of these incredible prehistoric marine animals, offering a glimpse into a time when the oceans were ruled by true titans.
The Megalodon is probably the most well-known animal on this list, and not without reason. This gigantic shark, which lived up to 25 million years ago, could reach the size of a school bus. Although often mistakenly presented as a contemporary of the dinosaurs, the Megalodon lived long after their extinction.
With an estimated length of up to 60 feet, this super shark was one of the largest predators in maritime history and swam in the warm oceans of the earth until the beginning of the last ice age.
The Liopleurodon, a gigantic marine reptile from the Jurassic era, would not be out of place in a scene from “Jurassic Park”. Although the exact size of these creatures is disputed, the general consensus is that they were about 6 meters long, with a fifth of that consisting of a terrifying, tooth-rich head. These predators were not incredibly fast, but extremely agile and could perform short, rapid attacks, similar to crocodiles.
The Basilosaurus, despite its name and appearance, was actually a whale and not a reptile. This ancestor of modern whales could reach a length of 15 to 26 meters. It is described as the closest approach to a whale crossed with a snake due to its long and slender body. Imagine swimming with a 20-meter-long alligator-snake-whale!
The Jaekelopterus rhenaniae, one of the largest arthropods that ever lived, reached a length of more than 2.5 meters. These ‘sea scorpions’ were armored and equipped with claws, making them a terrifying sight. But do not fear, they became extinct before the dinosaurs, during the Permian-Triassic mass extinction.
The Dunkleosteus was a true powerhouse of the sea. This 9-meter-long creature was a carnivore that dominated its era. Instead of traditional teeth, the Dunkleosteus had bony ridges, similar to those of a turtle, which functioned as a deadly weapon. With a bite force of up to 8,000 pounds per square inch, this giant fish was on par with the strongest biters in history, such as crocodiles and the Tyrannosaurus rex.
The skull of the Dunkleosteus showed that the animal could open its mouth in just one fiftieth of a second, effectively ‘vacuuming’ food into its mouth. The ‘teeth’ of the Dunkleosteus changed as the fish aged, from a solid, rigid jaw to segments that made it easier to hold prey and bite through the armor of other armored fish.
The Mauisaurus, named after the Maori god Maui, had a neck as long as 15 meters. With a total length of about 20 meters, this gigantic marine animal was an impressive presence in the Cretaceous seas. It lived in the area now known as New Zealand, a region always known for its terrifying fauna.
The Kronosaurus, a short-necked pliosaur similar to the Liopleurodon, was a terrifying marine reptile. Although the exact size is disputed, it is believed to have been about 9 meters long. But more impressive are the long teeth in its mouth, about 30 centimeters in length. This predator is named after Cronus, the king of the ancient Greek Titans. The Kronosaurus, with a head of about 2.5 meters, could theoretically swallow a full-grown human in one go. It is suggested that they, like modern sea turtles, possibly crawled onto land to lay eggs.
The Helicoprion was a unique shark of about 4.5 meters, with a distinctive ‘tooth whorl’ in the lower jaw. Due to this tooth structure, this sea monster appears like a cross between a circular saw and a shark. Although there is some discussion about the exact placement of these teeth, they were certainly carnivores. The Helicoprion survived the Permian-Triassic mass extinction, suggesting that they may have hidden in deep seas.
The Livyatan was a carnivorous whale that ate other whales. This gigantic whale had the largest teeth of any animal that used its teeth for eating, with teeth up to 36 centimeters long. They lived in the same oceans and competed for food with the Megalodon. With a head 3 meters long and equipped with echolocation equipment, they were extremely effective in murky water. This whale is named after both the biblical Leviathan and Herman Melville, the author of Moby Dick.
The Plesiosaurus, often confused with the dinosaurs, was actually a large marine reptile that lived during the early Jurassic era. With a long, flexible neck, a small head, and a broad, turtle-like body, this sea monster was a unique presence in the prehistoric oceans. Plesiosauruses could grow up to 15 feet long and were probably fast swimmers. Their long necks allowed them to perform surprise attacks on unsuspecting prey, making them effective hunters. Their mysterious appearance has contributed to numerous legends and myths, including that of the famous Loch Ness Monster.