Halisaurus (Greek for "ocean lizard"); pronounced HAY-lih-SORE-us
Oceans of North America and western Europe
Late Cretaceous (85-75 million years ago)
Size and Weight:
About 12 feet long and a few hundred pounds
Relatively small size; sleek body
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; like its fiercer descendants, this early, sleek mosasaur (just like its closest relative, Eonatator) more likely fed on fish and smaller marine reptiles.