Current perspectives on non-mineralized soft tissues in non-avian dinosaur fossils

Despite extensive published literature, skepticism about the claim of original soft tissues persists and the subject remains controversial. Data regarding the frequency of soft tissue findings are still scarse and those that have already been systematized are dispersed in the literature, which leads the idea of soft tissues to be associated with isolated phenomena. This article presents a review of the relevant literature, published in the last 50 years, in order to better understand the frequency of non-mineralized soft tissue findings in non-avian dinosaur fossils, and the time limits for expected survival of these biomolecules. The results identified 52 papers describing preserved organic material, considered geologically, geographically and taxonomically comprehensive. Still, it is believed that this frequency is underreported due to the current resistance in accepting these findings as being from organic remnants. The prediction is that acquisition of new technologies will turn such findings as the norm and not the exception