First occurrence of a fish otolith from the Eocene Fur Formation, Denmark

Bony fishes are among the best represented macrofossils from the earliest Eocene Fur Formation of Denmark. However, until now, otoliths from this formation have never been reported. Here we describe the first otolith from the Fur Formation, which was found isolated in a carbonate concretion. The specimen exhibits the typical features of an argentinoid otolith. To date, only a single argentiniform species, based on skeletal remains, has been documented from the Fur Formation – Surlykus longigracilis Schrøder & Carnevale, 2023 – which also represents the most abundant teleost species. Therefore, we refer the isolated otolith to Surlykus longigracilis. The discovery of this otolith offers the opportunity to review the many argentiniform otolith-based taxa known from the Paleocene of Denmark. One species is now also placed within the genus Surlykus - S. procerus (Schwarzhans, 2003) and another argentiniform otolith-based taxon from the Paleocene of Denmark is described – Pseudonansenia hauniensis n. gen., n. sp.