Extraordinary adaptations
20 Scary Prehistoric Sea Creatures to Explore
Armoured jaws, slicing teeth, coiled tooth whorls and grasping limbs: explore the anatomy of ancient aquatic hunters, from early seas to the age of giant sharks.
Explore the animals 20 ↘
How this list was selected
An editorial selection based on feeding anatomy and striking appearance, not a scientific fear or danger score. These animals lived at different times; most never encountered humans. Sea scorpions also occupied coastal and brackish settings. Plesiosaurs and mosasaurs were reptiles, but not dinosaurs; their diets and hunting styles differed.
In this guide 20
Explore the animals
20 atlas recordsAbout 23–3.6 million years ago
Megalodon
Otodus megalodon
Its hand-sized teeth belonged to a giant shark specialized in hunting marine mammals.
Warm oceans worldwide
About 82–66 million years ago
Mosasaurus
Mosasaurus hoffmannii
A giant marine lizard propelled by a deep tail fin patrolled Late Cretaceous seas.
Europe · North America · Open oceans
About 382–358 million years ago
Dunkleosteus
Dunkleosteus terrelli
Sharpened jaw plates replaced teeth in this heavily armored apex fish.
Seas of North America · Europe · North Africa
About 9.5–8.9 million years ago
Livyatan
Livyatan melvillei
Huge teeth in both jaws armed a macropredatory sperm whale.
Southeastern Pacific · Present-day Peru
About 125–100 million years ago
Kronosaurus
Kronosaurus queenslandicus
A massive pliosaur skull powered attacks on large marine prey.
Australian inland sea
About 166–155 million years ago
Liopleurodon
Liopleurodon ferox
A broad skull and four powerful flippers belonged to a leading Jurassic marine predator.
European seas
About 150–147 million years ago
Funke's Pliosaur
Pliosaurus funkei
A skull nearly two meters long and huge teeth formed an apex-predator bite apparatus.
Arctic open sea · Svalbard, Norway
About 89–75 million years ago
Tylosaurus
Tylosaurus proriger
A solid snout projected beyond the teeth as this giant mosasaur hunted fish, turtles and other reptiles.
Western Interior Seaway · North America
About 41–34 million years ago
Basilosaurus
Basilosaurus isis
This long-bodied early whale still carried tiny external hind limbs.
Tethys Sea · North American coasts
About 100–66 million years ago
Xiphactinus
Xiphactinus audax
Its huge upturned mouth could swallow fish nearly half its own length.
Open seas · North America and Europe
About 290–250 million years ago
Helicoprion
Helicoprion davisii
Its spiral tooth whorl worked like a permanent slicing blade inside the lower jaw.
Coasts of Pangaea · North America, Russia and Australia
About 157–145 million years ago
Dakosaurus
Dakosaurus maximus
A short deep skull carried serrated blades, while this marine crocodile's body had transformed into four flippers and a fishlike tail.
European continental-shelf seas · Present-day Germany, France and Britain
About 80.5 million years ago
Elasmosaurus
Elasmosaurus platyurus
An extraordinarily long neck let this marine reptile approach prey with a small head.
Western Interior Seaway of North America
About 189–182 million years ago
Ichthyosaurus
Ichthyosaurus communis
A streamlined reptile converged on the body plan of dolphins while retaining enormous eyes.
Shallow seas of Western Europe
About 521–508 million years ago
Anomalocaris
Anomalocaris canadensis
A meter-long swimmer with grasping frontal appendages was a giant of Cambrian seas.
Laurentian shallows · Present-day Canada
About 470–450 million years ago
Cameroceras
Cameroceras trentonense
A long straight shell housed one of the largest predators of Ordovician seas.
Laurentian shallows · Present-day North America
About 470–460 million years ago
Endoceras
Endoceras giganteum
A straight conical shell several meters long made it one of the most conspicuous large cephalopods of Ordovician seas.
Shallow seas of Laurentia and Baltica
About 428–423 million years ago
Pterygotus
Pterygotus anglicus
Flattened swimming paddles and great toothed claws made it a formidable hunter in Silurian water.
Estuaries and shallow sea · Present-day Britain
About 422–414 million years ago
Acutiramus
Acutiramus cummingsi
Its long pincers carried slanting blades suited to holding or slicing soft prey.
Estuaries, lagoons and shallow seas · North America
About 432–418 million years ago
Eurypterus
Eurypterus remipes
Paddle-shaped hind limbs carried this sea scorpion through shallow coastal water.
Laurentian shallows and lagoons · Present-day New York
