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