First Eocene record of a bangialean rhodophyte (the endolithic microboring Conchocelichnus seilacheri) and coralline red algae from the Pacific Coast of North America

Microborings made by bangialean rhodophytes and classified as Conchocelichnus occur as filamentous traces within living stylasterid corals or mollusc shells. These microborings have a fossil record spanning Ordovician to Recent within organic calcareous substrates such as mollusc and brachiopod shells, crinoid columnals, corals, and even sponges. The ichnotaxon Conchocelichnus seilacheri, based on microborings within Oligocene bivalves from Germany and Recent shells from the Bahamas has now been discovered in the tube walls of the spirorbid polychaete Neodexiospira vanslykei from the late Eocene basal part of the Lincoln Creek Formation in western Washington State, USA. Our research thus represents the first known interaction of endolithic traces Conchocelichnus seilacheri within fossil polychaete tubes and the first Eocene record of these microborings from North America. Neodexiospira vanslykei was also associated with the calcareous rhodophyte Corallina sp., representing the first Cenozoic record of Corallina from the Pacific Coast of North America.