Endobiotic cornulitids in Upper Ordovician tabulate corals and stromatoporoids from Anticosti Island, Quebec

A new species of endobiotic cornulitid, Cornulites celatus n. sp., has been discovered within Upper Ordovician tabulate corals and stromatoporoids from Anticosti Island, Quebec. This finding extends the known stratigraphic range of cornulitids in commensal relationships with these organisms back to the Upper Ordovician, previously thought to begin in the Silurian period. The study also reveals a more limited paleoenvironmental distribution for C. celatus compared to its principal coral host, Propora conferta, suggesting environmental specificity in their association. Growth interference patterns indicate a commensal relationship between the endobiotic cornulitid and its hosts, including Paleofavositessp., Acidolites arctatus, A. compactus, and Ecclimadictyonsp. The diagnosis of Cornulites is emended to include forms with a distinctive two-layered shell wall, characterized by an outer layer of prismatic calcite.

Dixon, O. A. (2010). Endobiotic cornulitids in Upper Ordovician tabulate corals and stromatoporoids from Anticosti Island, Quebec. Journal of Paleontology, 84(3), 518–528. https://doi.org/10.1666/09-129.1