Fossils themselves, and the sedimentary rocks they are found in, are very difficult to date directly. Instead, other methods are used to work out a fossils age. These include radiometric dating of volcanic layers above or below the fossils or by comparisons to similar rocks and fossils of known ages.
How do they date dinosaur fossils?
Todays knowledge of fossil ages comes primarily from radiometric dating, also known as radioactive dating. Radiometric dating relies on the properties of isotopes. These are chemical elements, like carbon or uranium, that are identical except for one key feature -- the number of neutrons in their nucleus.
How old is a dinosaur fossil?
A fossil is any evidence of prehistoric life (plant or animal) that is at least 10,000 years old.
Whats the oldest dinosaur alive today?
Nyasasaurus parringtoni is currently the oldest known dinosaur in the world.