100-million-year-old conifer tissues from the mid-Cretaceous amber of Charente (western France) revealed by synchrotron microtomography

International audienceBackground and Aims Terrestrial plant remains in fossilized tree resin are relatively common. However, histologyand preservation of plants entombed in Cretaceous ambers remain poorly known. We report an exquisitely preservedconifer leafy axis from 100-million-year-old opaque amber of western France that is assignable to Glenrosacarentonensis Moreau, Ne´raudeau, Tafforeau & De´pre´. The purpose of this paper is to discuss the taphonomy andthe use of microtomography for studies of palaeobotanical remains in amber. Key Results The conifer leafy axis described is preserved in three dimensions. Despite desiccation of the specimenwithin the surrounding amber, the cuticle, as well as most of inner tissues, is preserved in three dimensionsdown to the cellular level. Epidermis, palisade parenchyma, spongy parenchyma, transfusion tracheids and vascularbundles are clearly distinguished. Conclusions Gross morphology and histology of the specimen were revealed using synchrotron microtomography,allowing an unprecedented resolution for the study of soft-bodied plants entombed in amber. The study revealsa peculiar combination of authigenic and duripartic preservation as well as permineralization, and highlights thecomplexity of taphonomic processes that can occur in amber inclusions. This fossil demonstrates the difficulty ofstudying amber-preserved plant remains under certain conditions