Dinosaurs are not mentioned in the Bible. Some say that leviathan (Job 3:8, 41:1, Ps 74:14, etc.), is a dinosaur, but this does not make sense. Whatever leviathan is, it surely is not a dinosaur. It does not even make sense that God would mention dinosaurs to the Jews because they would have had absolutely no idea what God was talking about. The Jews had no concept of the earth being hundreds of millions of years or billions of years old. They knew nothing of fossils or extinct creatures. Remember that the Bible is not a science book. It was not written to explain the existence and role of bacteria or galaxies or atoms. If God had discussed these topics it would not have helped his purpose, which was to reveal himself to his people. It also would have confused them. The Jews did not even have words for microbes or dinosaurs or submicroscopic particles.
Bottom line, the Bible is not useful for deciding the question about dinosaurs. The question about dinosaurs is to be settled from the physical evidence. The physical evidence is clear. Obviously dinosaurs existed. We have tens of thousands of fossils of these strange and amazing creatures. Their fossils are never mixed with those of modern creatures. They are always found below fossils of more modern species. They lived a very long time ago. Various dating techniques tell us they lived from about 240 million years ago, becoming extinct about 65 million years ago.
Some people believe that the Bible states the earth is only a few thousand years old. To them, the existence of dinosaurs is a big problem because it is quite obvious that they lived much farther in the past than a few thousand years ago. The problem with this position is that the Bible does not say the earth is only a few thousand years old. I discuss the issues surrounding the question of the age of the earth in some detail in my book "Is There a God?" which is available at www.ipibooks.com. You will find several articles at the web site on this as well.
Perhaps the young-earth believers are right. Perhaps the earth is indeed only a few thousand years old. However, if that is the case, then there is the problem of the dinosaur fossils. If the earth is only a few thousand years old, then the implication is that, despite the fossil evidence, dinosaurs did not actually exist. The only remaining way to save this view is to conclude that God created the earth with an appearance of age, including with dinosaur fossils and coal and oil already in the ground. This seems an unlikely scenario, but who knows the mind of God and what he might have done.
To me, the obvious conclusion is that the earth is quite old and that dinosaurs lived a very long time ago. The Bible does not mention dinosaurs or trilobytes or any other truly ancient creatures, which is not surprising given the audience of the Old Testament, which leaves us to look at the evidence and decide for ourselves.
John Oakes, PhD