What was the Leviathan?
"In that day the lord with his sore and great and strong sword shall punish leviathan the piercing serpent, even leviathan that crooked serpent; and he shall slay the dragon that is in the sea." (Isaiah 27:1)
He is also said to "play" in the "great and wide sea" (Psalm 104:25-26). God's description in Job 41 says "a flame goeth out of his mouth" (v. 21), and "he maketh the deep to boil like a pot" (v. 31). The entire description is awesome! Whatever a leviathan might have been, it was not a crocodile!
Perhaps, therefore, the mysterious and notorious extinction of the dinosaurs is a secular prophecy of the coming Day of Judgment, when God "shall punish leviathan" (Isaiah 27:1), and the "devil that deceived them" will be "cast into the lake of fire . . . and shall be tormented day and night for ever and ever" (Revelation 20:10).