Hi all, I'm new here and have a rather simple question... how are objects in the earth's crust, such as fossils, dated? I understand that 40,000-65,000 years is the average availability of years that certain organic materials can be dated with carbon-14 dating, so how are numbers of years such as the arrival of the dinosaurs 250 million years ago discovered? This is a topic my uncle and I frequently argue on. He's a fundamentalist Christian and states the earth is around 10,000 years old (something I get nearly furious with every time we discuss the issue) and of course this statement isn't based on science, but I wouldn't know how to respond if he asked me HOW we know that dinosaurs first walked the earth 250 million years ago. I apologize if this is an extremely mundane topic for most of you (I imagine it is) and that if it gets in the way of many more complex issues. Thanks, C.J.