"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).
There is a remarkable animal called a "leviathan," described in the direct words of God in chapter 41 of Job. It is surprising that most modern expositors call this animal merely a crocodile. Our text plainly calls it a "piercing serpent . . . the dragon that is in the sea." 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!
In fact, there is no animal living today which fits the description. Therefore, it is an extinct animal, almost certainly a great marine reptile with "terrible teeth" and "scales" (vv.14-15) still surviving in the oceans of Job's day, evidently one of the fearsome reptiles that gave rise to the worldwide tales of great sea dragons, before they became extinct.
But that is not all. In ending His discourse, God called leviathan "a king over all the children of pride" (Job 41:34), so the animal is also symbolic of Satan, whose challenge to God instigated Job's strange trials. He is "the great dragon . . . that old serpent, called the Devil, and Satan, which deceiveth the whole world" (Revelation 12:9). 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). HMM