Reef-controlled distribution of Devonian microplankton in Alberta

Upper Devonian hystrichospherids of the off-reef Duvernay fades in Alberta, Canada, can be combined into three artificial groups that have different distribution patterns with regard to reefs. Simple spherical forms are widespread, from beds inter-fingering with reef carbonate into, off-reef areas. Thin-spined species are also widespread, but are seldom found within one mile of reefs. Thick-spined and polyhedral forms occur in off-reef strata, but seldom near reefs. All types increase in abundance with increasing distance from reefs. Plant spore distribution is useful in determining major current patterns. Forty species of hystrichospherids are described. New genera proposed are Duvernaysphaera, Multiplicisphaeridium, and Paleopedicystus. Micrhystridium and Leiosphaeridium are emended. New morphological structures of Chitinozoa are described and Hoegisphaera is proposed as a name for a new type of Paleozoic microfossil possibly allied to the Chitinozoa.