Marine reptileCretaceous
Mosasaurus
A fossil called Capelliniosuchus was first interpreted as a crocodile and later related to Mosasaurus.
Meet MosasaurusExplore the prehistoric world
Marine reptiles
Long-necked swimmers, streamlined hunters and powerful jaws. Explore the reptiles of prehistoric seas through fossil facts and their game illustrations.
20creatures in this group
3 game stages each
3 game stages each
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Meet the collection
Showing 1–20 of 20 creatures
Marine reptile
Marine reptileCretaceous
Tylosaurus
Its early study was linked to the rivalry between paleontologists Cope and Marsh.
Meet Tylosaurus
Marine reptileCretaceous
Platecarpus
Its diet is interpreted as based on fish and other small marine animals.
Meet Platecarpus
Marine reptileJurassic
Plesiosaurus
It had a small head, a long neck, a short tail and two pairs of large flippers.
Meet Plesiosaurus
Marine reptileCretaceous
Elasmosaurus
Its extremely long neck is one of its most recognizable features.
Meet Elasmosaurus
Marine reptileJurassic
Cryptoclidus
Its fine teeth suggest a diet of soft aquatic prey, such as fish and cephalopods.
Meet Cryptoclidus
Marine reptileJurassic
Liopleurodon
It was a marine reptile from the Jurassic, long before the last dinosaurs of the Cretaceous.
Meet Liopleurodon
Marine reptileCretaceous
Kronosaurus
Its name refers to Cronus, the titan of Greek mythology.
Meet Kronosaurus
Marine reptileJurassic
Ichthyosaurus
Mary Anning helped discover and bring attention to its fossils in nineteenth-century England.
Meet Ichthyosaurus
Marine reptileJurassic
Ophthalmosaurus
Its hydrodynamic body was reminiscent of that of a dolphin.
Meet Ophthalmosaurus
Marine reptileJurassic
Stenopterygius
The largest specimens reached approximately four meters in length.
Meet Stenopterygius
Marine reptileTriassic
Shonisaurus
Remains of numerous individuals have been found in the Luning Formation of Nevada.
Meet Shonisaurus
Marine reptileTriassic
Nothosaurus
Although its name means "false lizard", it was not a dinosaur.
Meet Nothosaurus
Marine reptileTriassic
Placodus
It inhabited warm seas of regions that today correspond to central Europe and China.
Meet Placodus
Marine reptileLate Cretaceous
Archelon
Archelon was a large marine turtle.
Meet Archelon
Marine reptileMiddle Triassic
Atopodentatus
Atopodentatus unicus had a broad, hammerhead-like snout with specialized teeth.
Meet Atopodentatus
Marine reptileLate Triassic
Henodus
Henodus chelyops had a broad armoured body and a short, box-shaped head.
Meet Henodus
Marine reptileTriassic
Dinocephalosaurus
Dinocephalosaurus was a marine reptile with an exceptionally long neck and a small head.
Meet Dinocephalosaurus
Marine reptileMiddle Triassic
Mixosaurus
Mixosaurus was an early ichthyosaur with a body plan less streamlined than the familiar later dolphin-like forms.
Meet Mixosaurus
Marine reptileEarly Jurassic
Rhomaleosaurus
Rhomaleosaurus was a large marine reptile with a powerful skull and four flippers.
Meet RhomaleosaurusA closer look at marine reptiles
Marine reptiles were not one single family of “sea dinosaurs”. Several reptile lineages independently adapted to life in water, producing different combinations of flippers, tails and body shapes.
Compare the group, period and fossil locations on each profile. Similar swimming shapes can evolve in distant relatives, so a dolphin-like outline does not make an ichthyosaur a mammal.
Were mosasaurs and plesiosaurs dinosaurs?
No. They were marine reptiles from lineages separate from dinosaurs. The same is true of ichthyosaurs, despite the word “saur” appearing in many of their names.
Further reading: Natural History Museum: Monsters of the Jurassic seas
AI-generated, stylized game illustrations. These designs and growth stages are imaginative, not scientific reconstructions. Open a profile for its fossil information and sources.