ABSTRACT

Dissociated columnals have been largely used for biostratigraphic purposes in many paleozoic series. Data obtained in the Lower and Middle Devonian of the Armorican massive and west-european regions show that columnals bring more precise informations on biodiversity and vertical distribution as given by calices. Paleobiogeography of paleozoic crinoids is also poorly investigated as indicated by scarcity of sketches ; some columnal taxa appear to be indicators of provinciality. The type of environment and some ecological conditions may also be detected by the distribution of taxa based on columnals ; examples are brought by laudonomphalids, gasterocomids and cupressocrinitds.