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Halisaurus (Wikimedia Commons)


Halisaurus (Greek for "ocean lizard"); pronounced HAY-lih-SORE-us


Oceans of North America and western Europe

Historical Period:

Late Cretaceous (85-75 million years ago)

Size and Weight:

About 12 feet long and a few hundred pounds


Probably fish

Distinguishing Characteristics:

Relatively small size; sleek body


About Halisaurus:

A relatively obscure mosasaur--one of the fierce, predatory marine reptiles that succeeded the plesiosaurs and pliosaurs of the preceding Jurassic period--Halisaurus had its moment in the pop-culture spotlight when the BBC nature show Sea Monsters portrayed it as hiding beneath shallow ledges and feeding on unsuspecting prehistoric birds like Hesperornis. Unfortunately, this is sheer speculation; this early, sleek mosasaur (just like its closest relative, Eonatator) more likely fed on fish and smaller marine reptiles.

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