More reptiles at sea

Plesiosaurs, pliosaurs, and turtles probably hauled themselves onto beaches to lay eggs, the way modern turtles do. Ichthyosaurs did not leave the water since they were fully adapted to life at sea and gave birth to live young. By the time the dinosaurs died out, all sea reptiles, apart from the turtles, had become extinct, too. The reason for this is as mysterious as the disappearance of

Fossil shell of the 12-in-long (30 cm) turtle Cimochelys

Fossil shells Fossilized ancient turtle shells show that these turtles had the same bony armor as modern turtles.

Fossil shells Fossilized ancient turtle shells show that these turtles had the same bony armor as modern turtles.

Archelon

Like its descendants, the modern turtles, Archelon may have returned to the same beaches every year to lay eggs. Both the adult Archelon and its eggs would have been vulnerable to predatory dinosaurs of that time.

Eye protection Ichthyosaurs were carnivores with long beaks - ,.

and pointed teeth. A bony ring surrounded each eye. These rings may have protected the eyes from high water pressure when diving to great depths.

Bony ring around eye

.Long jaw

\Sharp teeth

Large eye socket

Very thin, tooth-lined snout

Large eye socket

Very thin, tooth-lined snout

Shonisaurus was the largest ichthyosaur.

Stenopterygius Some fossilized adult ichthyosaur skeletons contain the skeletons of unborn young. This fossil of Stenopterygius is so well preserved it is possible to see the outline of the smooth body shape left by the skin.

Shonisaurus was the largest ichthyosaur.

Shonisaurus Giant Shonisaurus was 49 ft (15 m) long. Large groups of Shonisaurus skeletons have been found in North America. This suggests that they were prone to mysterious mass beachings (being stranded on a beach and dying), similar to present-day whales.

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