Late Ordovician jaw-bearing polychaetes from Anticosti Island, eastern Canada, and their biogeographic significance

A diverse assemblage of jaw-bearing polychaetes (scolecodonts) from the Late Ordovician rocks of Anticosti Island, eastern Canada, reveals strong biogeographic connections between Laurentia and Baltoscandia during a critical period in Earth's history. The study, which analyzed 10 samples containing approximately 30 species, documents several first occurrences for Laurentia, including the family Xanioprionidae and genera such as Pistoprion, Tetraprion, and Rakvereprion. The findings suggest that the closing Iapetus Ocean did not act as a barrier to polychaete dispersal, despite some Laurentian influence indicated by hadoprionid occurrences. Distinct differences between Katian Vauréal and Hirnantian Ellis Bay assemblages likely reflect local environmental changes rather than the initial phase of the Hirnantian mass extinction. This research sheds new light on the biogeographic dynamics during a pivotal interval in the evolution of marine life.

Hints, O., Tonarová, P., & Desrochers, A. (2016). Late Ordovician jaw-bearing polychaetes from Anticosti Island, eastern Canada, and their biogeographic significance. Canadian Journal of Earth Sciences, 53(7), 731–738. https://doi.org/10.1139/cjes-2015-0222