Carbon has a half life. By judging Carbon it is easy to see how long this piece of Carbon has been around for. Also, just digging in the ground enough can show when stuff was around.
Also, LOGICALLY, if there were predators around like dinosaurs in the time of Moses, wouldn't the bible mention that? Yes I have read the passage in Job that talks of dinosaurs, but it sounds like a fire breathing dragon to me, not a dinosaur. Also, don't you think human bones would be in close proximity to dinosaur bones. The argument that the world was made 6000 years ago by God is very illogical. There are too many things that don't connect. God didn't write the Bible, man did. Maybe God let evolution happen. Maybe God got the ball rolling for evolution, knowing where it would end up. If you stop thinking about what the bible says, and start thinking about things logically, then you will see evolution is quite obviously true. And even if it's not somehow, that the world was NOT created 6,000 years ago as it says in the bible.
Just answer me this, if there were dinosaurs around in the time of genesis, why weren't they talked about at all, AND why aren't dinosaur bones found anywhere NEAR human bones. I understand you have your beliefs, but these beliefs can be proven wrong. The belief in God however cannot be proven wrong. It is a matter of opinion, faith, and experience. Stop believing things blindly just because a book says it is true.