plesiosaur a water dwelling dinosaur. Biblical Leviathan.

A Hebrew word, livyathan, transliterated leviathan, is used six times in Scripture (e.g., Job 41:1; Psalm 104:26) and refers to some type of large, fierce sea creature (None is so fierce that dare stir him up ). The description of leviathan in Job 41 gives the impression of a strong yet graceful, unstoppable creature against which weapons are unavailing: “Nothing on earth is its equal” (Job 41:33).