How Do We Actually Know How Old Things Like Dinosaur Bones Are?

There’s an old joke told in natural history museums about a new tour guide showing around a group of visitors. Stopping before a dinosaur skeleton, he informs the group that the fossil remains are 80 million years and three weeks old. “How do you know that?” asks one of the visitors. “Because it was 80 million when I started,” says the guide. “And I’ve been here three weeks.” So how do we really know how old fossils like dinosaur bones are? This is an abridged version of a video on our channel TodayIFoundOut which you can check out and subscribe to here:    / @todayifoundout