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Marine Reptiles A to Z

They weren't technically dinosaurs, but these sleek plesiosaurs and pliosaurs, ichthyosaurs and mosasaurs, as well as other marine reptiles, filled the lakes, rivers and oceans of the Mesozoic Era. (See also the 10 Deadliest Marine Reptiles.)

Acamptonectes
This "rigid swimmer" was closely related to Ophthalmosaurus.

Aigialosaurus
An early "missing link" in mosasaur evolution.

Archelon
A dinosaur-sized turtle of the late Cretaceous.

Aristonectes
One of the last plesiosaurs left before the K/T extinction.

Askeptosaurus
An eel-like predator of the middle Triassic period.

Attenborosaurus
This plesiosaur was named after the documentarian David Attenborough.

Augustasaurus
An early marine reptile of the middle Triassic period.

Brachauchenius
One of the last pliosaurs of the late Cretaceous period.

Brachypterygius
This big-eyed ichthyosaur was a cousin of Ophthalmosaurus.

Californosaurus
Guess what state this ichthyosaur was discovered in?

Ceresiosaurus
A "pursuit diver" of the middle Triassic period.

Claudiosaurus
An iguana-like reptile of the late Permian period.

Clidastes
A small mosasaur of the Cretaceous period.

Corosaurus
The most advanced nothosaur yet identified.

Cryonectes
This "basal" pliosaur measured barely ten feet long.

Cryptoclidus
A classic, sleek, long-necked plesiosaur.

Cyamodus
This Triassic reptile looked uncannily like a turtle.

Cymbospondylus
A very large--and very ancient--ichthyosaur.

Dakosaurus
This fierce marine crocodile had a dinosaur-like head.

Dallasaurus
Guess what city this mosasaur was named after?

Dolichorhynchops
A typical pliosaur of the late Cretaceous.

Ectenosaurus
This mosasaur had unusually well-preserved skin.

Elasmosaurus
From head to tail, the longest plesiosaur that ever lived.

Endennasaurus
A shore-prowling thalattosaur of southern Europe.

Eonatator
This "dawn swimmer" was one of the first mosasaurs.

Eoplesiosaurus
This "dawn Plesiosaurus" preceded its namesake by millions of years.

Eurhinosaurus
This ancient ichthyosaur looked like a modern sawfish.

Excalibosaurus
This ichthyosaur was named after King Arthur’s sword.

Futabasaurus
The first plesiosaur ever to be discovered in Japan.

Gallardosaurus
This pliosaur was discovered in Cuba in 1946.

Geosaurus
This aquatic reptile may have spent its entire life in the sea.

Globidens
This sleek mosasaur had unusually round teeth.

Goronyosaurus
This mosasaur behaved a lot like a marine crocodile.

Grippia
The best specimen of this ichthyosaur was destroyed in World War II.

Guarinisuchus
This marine crocodile thrived shortly after mosasaurs went extinct.

Hainosaurus
One of the biggest mosasaurs that ever lived.

Halisaurus
Along with Eonatator, one of the earliest mosasaurs.

Henodus
This Triassic placodont looked remarkably like a modern turtle.

Hovasaurus
One of the first aquatic diapsid reptiles.

Hupehsuchus
This early marine reptile had extra digits in its hands.

Hydrotherosaurus
This "fisherman lizard" roamed the prehistoric coasts of California.

Hyphalosaurus
A common sight in China's Liaoning fossil beds.

Ichthyosaurus
A remarkably fish-like lizard of the Jurassic era.

Kaiwhekea
A smallish plesiosaur from New Zealand.

Keichousaurus
One of the oldest, and smallest, of all marine reptiles.

Kronosaurus
It made the great white shark seem like a guppy.

Lariosaurus
A small aquatic reptile of the Triassic period.

Latoplatecarpus
A close relative of (you guessed it) Platecarpus.

Leptocleidus
This pliosaur spent most of its time in shallow ponds.

Libonectes
An Elasmosaurus-like plesiosaur of the late Cretaceous period.

Liopleurodon
This mean-looking pliosaur was one of the biggest of all marine reptiles.

Macroplata
This aquatic reptile looked like a cross between a plesiosaur and a pliosaur.

Malawania
A dolphin-like ichthyosaur of the early Cretaceous period.

Mauisaurus
One of the few plesiosaurs to be discovered in New Zealand.

Megalneusaurus
This pliosaur rivaled Liopleurodon in size.

Mesosaurus
This reptile helped confirm the theory of continental drift.

Metriorhynchus
One of the most common crocodiles of the Jurassic period.

Mixosaurus
This "mixed lizard" may be the the missing link of ichthyosaurs.

Mosasaurus
The first giant aquatic reptile ever to receive a name.

Muraenosaurus
This plesiosaur had an exceptionally slender neck.

Nannopterygius
The most common ichthyosaur in the fossil record.

Neptunidraco
"Neptune's dragon" is the earliest identified metriorhynchid.

Neusticosaurus
One of the smallest marine reptiles yet identified.

Nothosaurus
A slim, fast swimmer with lots of teeth.

Omphalosaurus
This "button lizard" may or may not have been a genuine ichthyosaur.

Ophthalmosaurus
An ocean-dwelling ichythosaur distinguished by its large eyes.

Pachypleurosaurus
This Triassic reptile has proven hard to classify.

Pachyrhachis
An early Cretaceous ancestor of modern snakes.

Pannoniasaurus
The first identified freshwater mosasaur.

Paraplacodus
This early marine reptile fed on shellfish.

Peloneustes
This "mud swimmer" feasted on squids and mollusks.

Pistosaurus
This marine reptile was half plesiosaur, half nothosaur.

Placochelys
A turtle-like placodont of the late Triassic period.

Placodus
This blunt-headed reptile sucked shellfish off the ocean floor.

Platecarpus
The most common mosasaur of Cretaceous North America.

Platypterygius
One of the rare ichthyosaurs to survive into the Cretaceous period.

Plesiosaurus
This long-necked swimmer set the standard for aquatic reptiles.

Pleurosaurus
A marine ancestor of the modern tuatara.

Plioplatecarpus
A large, short-jawed mosasaur of Europe and North America.

Pliosaurus
A complete skeleton if this giant swimmer was recently found in Norway.

Plotosaurus
This fast, sleek predator represented the pinnacle of mosasaur evolution.

Polycotylus
This plesiosaur gave birth to live young.

Prognathodon
A strong-jawed mosasaur of the late Cretaceous.

Psephoderma
If a turtle mated with a horseshoe crab, the result might have been this reptile.

Rhomaleosaurus
One of the most fearsome predators of the Jurassic seas.

Shastasaurus
This ichthyosaur fed on soft-bodied cephalopods.

Shonisaurus
The largest ichthyosaur yet to be discovered.

Steneosaurus
An ocean-going crocodile of the Mesozoic Era.

Stenopterygius
A close relative of Ichthyosaurus.

Stereosternum
A tiny relative of the better-known Mesosaurus.

Styxosaurus
This long-necked swimmer was a relative of Elasmosaurus.

Taniwhasaurus
Its name is Maori for "water monster lizard."

Tanystropheus
This reptile's long neck looked like a rubber pencil.

Tanytrachelos
A close relative of the long-necked Tanystropheus.

Temnodontosaurus
A dolphin-shaped ichthyosaur that gave birth to live young.

Terminonatator
Not quite a Terminator, but close enough.

Thalassiodracon
This impressive-sounding plesiosaur was actually very small.

Thililua
Try saying its name ten times fast.

Trinacromerum
A speedy plesiosaur of the late Cretaceous period.

Tylosaurus
A slim, sleek mosasaur of the late Cretaceous.

Tyrannoneustes
This "tyrant swimmer" cut a very crocodilian profile.

Utatsusaurus
The most ancient ichthyosaur yet discovered.

Woolungasaurus
The remains of this plesiosaur were dug up in Australia.

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