Anoigmaichnus

Anoigmaichnus
Trace fossil classification

Anoigmaichnus is an ichnogenus of bioclaustrations (a type of trace fossil). Anoigmaichnus includes shafts perpendicular to host's growth surface or tilted (up to 45°); conical to cylindrical; circular to oval cross-sections; lacking separate wall. Their apertures are elevated above host's growth surface forming a short chimney-like structures. Anoigmaichnus is the worlds earliest known macroscopic endobiotic symbiont and it may have been a parasite. It occurs in the Middle Ordovician bryozoans of Osmussaar Island, Estonia.^[1]

References

1. Vinn, O.; Wilson, M.A.; Mõtus, M.-A. & Toom, U. (2014). "The earliest bryozoan parasite: Middle Ordovician (Darriwilian) of Osmussaar Island, Estonia". Palaeogeography Palaeoclimatology Palaeoecology. 414: 129–132. doi:10.1016/j.palaeo.2014.08.021. Retrieved 2014-01-09.