Turtle barnacles have been turtle riders for more than 30 million years

Abstract In contrast to other kinds of biological interactions, symbiosis is a scarcely investigated aspect the fossil record. This largely due taphonomic biases that often frustrate any attempt make strong case two organisms shared an intimate association in life. Among extant marine vertebrates, sea turtles (Cheloniidae and Dermochelyidae) bear broad diverse spectrum epibiotic symbionts, including specialists such as turtle barnacles (Chelonibiidae Platyleapadidae). Here, we reappraise early Oligocene (Rupelian) cheloniid skeleton, featuring remains cirripedes on exterior its entoplastron, from Rauenberg fossil-lagerstätte , southwestern Germany. The barnacle specimens are assigned Protochelonibia melleni extinct protochelonibiine species geologically oldest known member Chelonibiidae. light palaeoenvironmental considerations, given chelonibiids mostly epizoic symbionts turtles, conclude this unique resulted growth external surface plastron during lifetime. remarkable provides evidence chelonibiids, protochelonibiines, have been chelonophilic epizoans for more than 30 Myr. A survey trace body records shows platylepadids also likely old Rupelian their symbiotic with hosts. emergence modern-looking, turtle-dwelling lineages corresponds climate-driven phase major radiation taxonomic turnover among at Eocene–Oligocene transition.