ACRITARCS: Defined by Evitt (1963) as "an informal utilitarian, 'catch-all' category without status as a class, order or other supragenieric unit" comprised of "small microfossils of unknown and probably varied biological affinities consisting of a central cavity enclosed by a wall of single or multiple layers and a chiefly organic composition." Microscopic (5 - 240 micrometer) fossils with various form and sculpturing, ranging from types resembling dinoflagellates to those resembling chitinozoans. Primarily used in stratigraphic studies of marine sediments of the Paleozoic (540 - 120 Ma). Composition unknown, but resistant to palynological procedures. Ecological preferences, based on facies relationships suggest near-shore abundance.

Owen Davis 12/99