Small Cornulitids from the Upper Ordovician (katian) of Estonia

Two new cornulitid species, Conchicolites sutlemaensis n. sp. and C. parcecostatis n. sp., are here described from the Kõrgessaare Formation (middle Katian) of Estonia. The fauna of the Kõrgesaare Formation is especially rich in small cornulitids including Conchicolites sutlemaensis n. sp., C. parcecostatis n. sp., C. kroegeri, C. rossicus, Cornulites cf. shallochensis and C. sp. A. The muddy bottom cornulitid faunas appear to have been dominated by minute species of Conchicolites in the Late Ordovician. Among Conchicolites species, C. rossicus is most abundant in the Kõrgessaare Formation. The species of Conchicolites that are rare on hard substrates in limestones were likely adapted to life in soft bottom clay and muddy environments.