A critical review of the age of Baltic amber from the Samland Peninsula, Russia

ABSTRACT Baltic amber is the best known of all the inclusion-bearing ambers and is often washed up on the shores around the Baltic Sea. The Upper Blue Earth Member of the Prussian Formation is the main source of this amber, although it also occurs in beds above and below. The age of Baltic amber has been a subject of controversy for many years, but it is important to know what its most likely age is when studying the evolution of different animal and plant groups trapped in the amber, particularly taxa used in phylogenetic trees. A review of the different dating techniques confirms that dinoflagellate cyst biostratigraphy is the best method for dating the amber-bearing beds. Here we correlate the published dinocyst species records with the zonation schemes in the Geologic Time Scale 2020 to provide more accurate and up-to-date dating of these beds. The Prussian Formation is late Eocene (Priabonian) in age, 37.7–34 million years old, and the Upper Blue Earth Member is mid-Priabonian, 36–35 million years old. Amber from the Upper Blue Earth is considered to be the same age and, given that it is concentrated towards the base of the member, an age of 36 Ma can be used in phylogenetic trees. Baltic amber of unknown provenance is probably Priabonian in age.