Late Ordovician (Hirnantian) diploporitan fauna of Anticosti Island, Quebec, Canada: implications for evolutionary and biogeographic patterns

A rare discovery of Late Ordovician (Hirnantian) diploporitan echinoderms, including Holocystites salmoensis and an unidentified holocystitid, from the Ellis Bay Formation on Anticosti Island, Quebec, Canada, provides critical insights into their evolutionary origins and biogeographic patterns. These fossils extend the known ancestry of the Silurian Holocystites Fauna by at least 15 million years, challenging previous assumptions about its origination. The study highlights the significance of uncovering underrepresented time periods in Earth's history to better understand evolutionary transitions. By analyzing reefal facies and disarticulated crinoid ossicles, researchers offer a unique perspective on noncrinoid echinoderm dynamics during this pivotal geological boundary.

Sheffield, S. L., Ausich, W. I., & Sumrall, C. D. (2018). Late Ordovician (Hirnantian) diploporitan fauna of Anticosti Island, Quebec, Canada: implications for evolutionary and biogeographic patterns. Canadian Journal of Earth Sciences, 55(1), 1–7. https://doi.org/10.1139/cjes-2017-0160