Radiocarbon dating dinosaurs
Further, this 2017 paper in , Carbon fixation from mineral carbonates, confirms that cynobacteria in fossils get "virtually all" of their carbon from the bone substrate they are feeding on!
Therefore they cannot "contaminate" the 14c results because they will carbon "date" the same as the bone itself, for their percentage of modern carbon is identical to that of the bone.
(Further, there is a pretreatment process of repeated washes of acid/alkali/acid to remove any outer humic acid and debris.) Therefore creationists have been correct to dispute Mary Schweitzer, Lindgren, et al., as they've tried to explain away as microbial contamination the "modern" carbon in an endogenous biomaterial Mosasaur bone. (See also this post from a committed evolutionist in a battle royale with our old friend rsr.org/david-willis at the forum run by RSR host Fred Williams.) Regarding Libby's "no known natural mechanism" way of contaminating collagen, here's our RSR explanation of why this is.
If a specimen is purified to 95% collagen, or 98%, or 99%, etc., then approximately the same percent of the carbon in the fossil sample will be endogenous (i.e., original to the living animal). Because new carbon atoms will not original carbon atoms in the collagen molecule.
As a result of decomposition, to the extent that original carbon atoms were falling out of the tissue (so to speak), then to that extent you would no longer have collagen; rather, to that extent you would have humic acid.
Decomposing collagen cannot be "repaired" by free carbon atoms happening upon the decomposition.
As reported elsewhere also in limestone, fossilized wood, coal, marble, deep groundwater, geological graphite, Mesozoic-layer limestone, and the bones of dinosaurs including the ten described below.
Thus, where researchers find , "There is no known natural mechanism by which collagen may be altered to yield a false age." And as of 2019, there is still no known mechanism to contaminate collagen with modern carbon.
* Carbon 14 in Dinosaurs at Singapore's American Geophysical Conference: On how to date a dinosaur, Real Science Radio's Bob Enyart interviews Hugh Miller, a member of the international scientific team that presented at the 2012 AGU geophysical conference in Singapore, the carbon dating results from five respected laboratories around the world of bones from ten dinosaurs (from the Gobi Desert in China, from Europe, Alaska, Texas, and Montana). Yet each of these dinosaurs had plenty of radiocarbon (as expected in that virtually every relevant peer-reviewed paper on the topic confirms the presence of endogenous soft tissue in fossils; see Dinosaur Soft Tissue.com).
With the scientific breakthroughs and discoveries coming in daily, this is a great time to be alive!
So if a researcher can verify that he has a sample that has been purified to 99% collagen, for example, then he can be sure that all the carbon in that 99% of the sample is original.
Carbon dating has a certain margin of error, usually depending on the age and material of the sample used.