Has carbon 14 been found in fossils?

Yes, carbon 14 (${}^{14}C$) has been found in fossils. However, it is only useful in dating relatively recent organic matter, less than about 50,000 years old. After 50,000 years, there is too little carbon 14 remaining to measure accurately due to its half-life of 5,730 years. It is important to note that not all fossils are millions of years old. There are many human, plant, and animal fossils that are younger than 50,000 years old and can be dated using carbon 14.