Carbon dating and errors
Libby, the discoverer of the C14 dating method, was very disappointed with this problem.
So they start with the assumption that dinosaurs lived millions of years ago, then manipulate the results until they agree with their conclusion. So why is it that if the date doesn't fit the theory, they change the facts?
Older carbon dating techniques directly detected decays of C14 atoms. The most common contaminant is nitrogen, 0.1% in gem-quality diamonds.
The problem: If the material is too old, the small amount of C14 present may not decay in the measurement interval. Nearby radioactive material could trigger exactly the same C14 production process from nitrogen as occurs in the upper atmosphere, albeit at a much reduced rate.
The age they came back with was only a few thousand years old. And kept their theory that dinosaurs lived "millions of years ago" instead. They then use potassium argon, or other methods, and date the fossils again.
This date did not fit the preconceived notion that dinosaurs lived millions of years ago. They do this many times, using a different dating method each time.