He said that his team and the laboratories they employed took special care to avoid contamination.
That included protecting the samples, avoiding cracked areas in the bones, and meticulous pre-cleaning of the samples with chemicals to remove possible contaminants.
In fact, the article by Leppert raises a number of additional issues (e.g.The predominant suite of elements present and their relative percentages (including the 3.4% carbon!) are about what one would expect to find in hydroxyapatite and calcite, two of the commonest minerals present in ordinary dinosaur fossils.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 preferred method of dating dinosaur fossils is with the radiometric dating method.