When bioclasticity began? Taphonomy of Cloudina shell concentrations, Itapucumi Group, Ediacaran, Paraguay - Warren, Lucas; Simões, Marcello Guimarães; Fairchild, Thomas R.; Riccomini, Claudio; Boggiani, Paulo César; Quaglio, Fernanda; Freitas, Bernardo Tavares (Congresso Brasileiro de Geologia, 2012)