The Role of Carbon 14 in Human Archaeology

You can use this for basically anything that's died in the last you know maybe 50,000 years because those things were accumulating carbon 14 as they were alive and participating in the biosphere. As soon as they died then they stopped and the carbon 14 started to decay away. By the time you have petroleum there's no carbon 14 and you start losing carbon 14 when you die so can you use this for is this helpful for like certain kinds of fossils what kind of things have we used this for so far?