Among the general population, there are many misconceptions and assumptions made about radiometric dating methods used to arrive at the age of fossils and the supporting environmental materials in which they were buried. The most widely known method for dating organic material is, of course, or carbon-14, an unstable radioactive isotope of carbon. As we know, life on earth is carbon-based. When lifeforms die, the concentration of the stable isotopes of carbon (12C and 13C) remain constant while begins to decay (becoming 14N/nitrogen-14) at a predictable rate until there is none left.
The dating process makes assumptions amount of 14C present when the animal or plant died and compares it to the amount of existing 14C in the sample at the time of measurement. The rate of radioactive decay is measured in half-lives (1 half-life = 5730 years) and the concentrations of 14C, 13C and 12C are usually measured today using an Accelerator Mass Spectrometer (AMS).
After 10 to 12 half-lives, for most samples, 14C levels will have fallen below the limit of detection of the AMS. This is why specimens, believed to be more than 70,000 years old, are not normally subjected to 14C dating.
That brings us to an area needing further exploration, analysis and review which is the anomaly that dinosaur soft tissue from deep time, that has undergone radiometric testing, repeatedly returns positive results for the presence of 14C when the overwhelming expectation is for a negative result. What is/are the likely reason/s for this?
There are now more than 120 papers in peer-reviewed journal articles reporting soft tissues in dinosaur and other deep-time organic remains. These scientific papers describe biological material, including tissue and DNA, remaining inside fossils. A full list, which is being continually updated, is provided here: *List of Biomaterial Fossil Papers
Example papers for this topic:
(67) Type 1 Collagen in Cretaceous mosasaur humerus 2011
*This list of biomaterial papers can provide useful information for research and posting on topics within the Dinosaur Project Community. Thanks to researchgate.net for making this list freely available.