So recently, bones of a new hadrosaurid Ugrunaaluk have been found. In the published scientific article it was stated that the bones were unpermineralised.

On wikipedia I read that is a proces of fossilisation, and that MOST dinosaur bones are permineralised.

My questions: How can the bones of a dinosaurs remain unpermineralised for so long? If not all, but most dinosaur bones are permineralised, what are the rest of them? Is there another possible proces of fossilisation?

thanks for your post and having read the paper that you referenced (A new Arctic hadrosaurid from the Prince Creek Formation (lower Maastrichtian) of northern Alaska by Mori, H., Druckenmiller, P.S., and Erickson, G.M. in Acta Palaeontologica Polonica) I too was very puzzled!

I therefore contacted Professor Tony Fiorillo who is the world expert in this field (and whose many papers are cited in the Mori ppaer) who responded as follows (I have highlighted the text in bold for emphasis):

The Mori et al. paper states that the bones are "typically uncrushed and unpermineralized" and cite two papers; Gangloff and Fiorillo (2010) and Fiorillo et al. (2010). While the preservation of dinosaur bones at the Liscomb Bonebed is exquisite, the bones are indeed permineralized. In Gangloff and Fiorillo (pg. 300), we discuss the common to abundant occurrence of minerals such as pyrite, calcite and chalcedony (microcrystalline quartz) within the dinosaur bones collected. All of these minerals are commonly introduced during the permineralization process. Further in Gangloff and Fiorillo (2010) there is a great deal of discussion in the text and in the figures about the fractured nature of many bones due to the freeze-thaw process present along boundaries of permafrost.

In Fiorillo et al. (2010) we did not focus on any of the mineralogical aspects of bone preservation so I am puzzled as to why this paper is used in this part of the Mori et al. paper.

I hope this helps clarify the question raised on your website. The bones from the Liscomb Bonebed are remarkable but they are indeed fossilized and they are indeed permineralized.