Polish research team, including: palaeobiologist Dr Daniel Tyborowski from the Museum of the Earth of the Polish Academy of Sciences (PAN), radiation chemist Prof. Magdalena Długosz-Lisiecka from the Interdepartmental Institute of Radiation Research of the Lodz University of Technology and geologist Dr Marcin Krystek from the Geological Museum in Łódź was the first in the world to explain why radioactive fossils are formed and what fossilization processes may lead to it.  

The research focused on the measurements of natural gamma radioactivity with the use of spectroscopic methods. They included several dozen invertebrate and vertebrate fossils from different geological periods and from different places. It was found that the formation of radioactive fossils occurs in two cases: when the specimen is composed of phosphates or when the burying environment of the remains was enriched with phosphates, i.e. when the fossils, which were not originally phosphated, were subject to phosphatization.

The research publication appeared in the journal “Chemosphere”:
https://www.sciencedirect.com/science/article/abs/pii/S0045653521019160