Contamination of this kind amounting to 1 percent of the carbon in a sample 25,000 years old would make it appear to be about 1,500 years younger than its actual age.
The claims are really quite spectacular, when taken at face value, and therefore should be examined thoroughly.
In this answer, I will try to go through this story in great detail, (hopefully) exposing the reasons why this work is not taken seriously by scientists.
Clearly proper sample decontamination procedures are of particular importance in the dating of very old artifacts It is clear that the sample provided by Miller did not under go any 'sample decontamination procedures' at all, and it is therefore strongly questionable to which extent it can be used to obtain a good estimate of the age of the bones.
Furthermore, it appears less than certain that the carbon found in the bones actually had anything to do with them being dinosaur bones.
It's accuracy has been verified by using C-14 to date artifacts whose age is known historically.
The fluctuation of the amount of C-14 in the atmosphere over time adds a small uncertainty, but contamination by "modern carbon" such as decayed organic matter from soils poses a greater possibility for error. Thomas Seiler, a physicist from Germany, gave the presentation in Singapore.The age that these groups claim to find is usually on the order of thousands or tens of thousands of years old.The particular example you bring up is one of the most famous such cases.These, together with many other remarkable concordances between samples from different fossils, geographic regions and stratigraphic positions make random contamination as origin of the C-14 unlikely".There is a lot of discussion about this issue on this internet, so I think this question may be worth addressing seriously.In the article by Leppert, we find: Hugh Miller generously provided me with a copy of the elemental analysis of one of their dinosaur fossils.