This question can be answered the same way we can explain why the words “telephone” and “computer” are not in the Bible: It wasn’t invented yet. The King James Version of the Bible was written in 1611, but the word “dinosaur” was not invented until 1841, which was 230 years later. However, the KJV does include a certain word called “dragon,” and when put in the context of certain Biblical passages, “dragon” describes the characteristics of dinosaurs. Cultures around the world have/had words used to describe dinosaurs. You can see a listing of those words here.