There’s a new fossil remora in Stuttgart – Oligoremora! A remora from the Oligocene of . . . Baden-Württemberg. Our fossil collection definitely has a local theme. I’ve mentioned the Oligocene fossil site of Rauenberg before (it’s an important one), and this fish is from the same quarry.
What’s a remora? They’re actually fairly awesome. Remoras are a group of marine fishes in which the first dorsal fin has been modified into an adhesion disc that they use to attach to larger animals, such as a shark, ray, whale, or turtle. The remoras save energy by not swimming or pumping water over the gills (the fish version of breathing), and in turn keep the host clean of parasites and dead skin.
A range of potential remora hosts are known from Rauenberg, including sharks, turtles, and dugongs. While living species of remoras are quite specific in their host preferences, pinpointing Oligoremora’s host is not possible at this point. It is also possible that host preferences appeared more recently in the evolutionary history of remoras.
The steps leading up to an adaptation as specific as the remora adhesive disc and ride-along lifestyle are bound to be interesting. Based on fossil occurrences and molecular data, it is estimated that the adhesion disc appeared at most seven million years before the widespread appearance of remoras, including Oligoremora, in European seaways in the early Oligocene. All of these early Oligocene remoras were equipped with a fully functional adhesion disc, and so the earliest evolutionary steps towards this specialized structure and lifestyle still remain poorly understood.
Friedman, M., Johanson, Z., Harrington, R. C., Near, T. J., & Graham, M. R. (2013). An early fossil remora (Echeneoidea) reveals the evolutionary assembly of the adhesion disc. Proc. R. Soc. B 280(1766).
Micklich, N., R. Gregorová, A. F. Bannikov, D.-S. Baciu, I. Grădianu, and G. Carnevale. 2016. Oligoremora rhenana n. g. n. sp., a new echeneid fish (Percomorpha, Echeneoidei) from the Oligocene of the Grube Unterfeld (“Frauenweiler”) clay pit. Paläontologische Zeitschrift.