Read Job 40:15-24. Job was questioning God because of his suffering, and so God comes and challenges Job with His creation. Many people say, “Job 40 can’t be speaking of a dinosaur.” They say that, not because the description doesn’t fit, but because of their preconceived conception that man and dinosaurs didn’t live together.
The margin of the NIV says, “Possibly the hippopotamus or the elephant.” Something to keep in mind—the footnotes were not in the original. Well, the tail of an elephant or hippo is like a twig, not a cedar (most dogs have longer tails). Throughout the Scriptures, cedars were known for their great size and length. Nothing on earth today fits this description, but a sauropod type of dinosaur does. The largest we have found was over 120 feet long. That sounds to me like the “chief”—not a hippo.
And then in Job 41, God describes the Leviathan (Isaiah 27:1 calls it the dragon in the sea). The margin of the NIV says, “Possibly the crocodile.” But the description again doesn’t fit any animal alive today. Besides, man has never had a problem catching crocodiles, even primitive tribes, but God says in Job 41 that Leviathan couldn’t be caught.
Some think this was just a mythical creature since it speaks of it breathing fire. And yes, Job is a poetic book and those could just be poetic descriptions. But not necessarily. Impossible you say? What about the electric eel that can produce enough electricity to stun a horse? If the electric eel was extinct and all we could find were its fossils, would we be able to know that it could generate electricity? Nope. What about the firefly and anglerfish that can produce light? What about the bombardier beetle that can fire a boiling mixture of chemicals at its enemies that is 212 degrees Fahrenheit? Why couldn’t God have created certain water-living reptiles that were capable of expelling hot gaseous fumes that could ignite? Most animals produce methane anyway, which is a flammable gas. Stories of fire-breathing dragons have circulated for thousands of years.
Also, keep in mind that Behemoth and Leviathan were included along with real creatures that Job knew about. Read Job sometime.
In Isaiah 30:6, Isaiah speaks of flying serpents. I also find it interesting that Herodotus, the Greek Historian who lived around 450 BC wrote about flying serpents in Arabia. He talked about finding their bones and described their snake-like bodies and bat-like wings. And the Jewish historian from the first century, Josephus, wrote about Moses and the Israelites having a difficult time passing through a particular region because of the presence of flying serpents. I think they were speaking of one of the pterosaurs like the pterodactyl, pteranodon, or rhamphorhynchus.