Rugose corals of the Late Ordovician to earliest Silurian Vaureal, Ellis Bay and Becscie formations, Anticosti Island, Quebec

The rugose corals of the Late Ordovician (Richmondian-Gamachian) to earliest Silurian (Rhuddanian) Vaureal, Ellis Bay and Becscie formations of Anticosti Island, Quebec, include 19 species belonging to 14 genera and five families, with three additional species placed in open nomenclature. Of the 19 species, five are new: Streptelasma n. spp. 1 and 2, Bodophyllum n. sp., Rhegmaphyllum n. sp. and Palaeophyllum n. sp.; Diversity is generally low in the entire stratigraphic interval except in bioherms. The Vaureal fauna is of low to moderate diversity (one to five species at a particular locality and stratigraphic interval), characterized by Red River-Stony Mountain Province species, four of which are also found in the Stony Mountain Formation of southern Manitoba. Two of the seven Vaureal Formation species disappear in the Mill Bay Member (first observed extinction interval). The Ellis Bay fauna is of low to moderate diversity (one to five species per locality) below the uppermost member and is characterized by "continental margin" forms. Three holdovers from the Richmondian disappear in the Prinsta Member (second observed extinction interval). The uppermost Ordovician Laframboise Member is distinguished by reef development and a peak in rugosan species diversity (seven species at one locality). The Ellis Bay fauna has affinities with Baltoscandian and Chinese rugose coral faunas in terms of generic makeup; no species are common to both the study area and non-Laurentian realms. All but one Ordovician species, Eurogrewingkia pulchella, disappear at the systemic boundary, placing the local extinction maximum (seven species) stratigraphically higher than mass extinction intervals recorded for other taxa from Anticosti Island. The three observed extinction intervals correlate with known brachiopod extinctions and reefal crises in the study interval. The Becscie fauna is of low to moderate diversity (one to five [possibly six] species per locality), consists of different species from those of the Ellis Bay Formation (except for E. pulchella which is present in the lowest 18 m), and is cosmopolitan in nature, including one species found at three other localities in North America and in Siberia and Iran. This fauna represents the earliest stage of rugose coral recovery from the end-Ordovician extinction.