Lower paleozoic chitinozoans and scolecodents from North Dakota

Chips from cores of the Red River and Stony Mountain Formations of Ordovician age and the Dawson Bay Formation of Devonian age in North Dakota were taken at three-foot intervals, dissolved in acid, and the residue examined for insoluble, pseudochitinous microfossils. Chitinozoa, an extinct order of rhizopod protozoans, were found in abundance along with lesser numbers of scolecodonts, the mouth parts of polychaete worms. Because the study was restricted to the core available at the North Dakota Geological Survey, which rarely included complete sections of the formations, a complete picture of the distribution of these forms must await the more extensive examination of well cuttings. However, the value of Chitinozoa in subsurface stratigraphic work in North Dakota is demonstrated, for many species are restricted to relatively narrow intervals extending over the entire state. Scolecodonts, because of parataxonomic problems and a more limited occurrence, do not appear to be as useful, but distinct faunal differences exist between Ordovician and Devonian forms. Twenty-one species in eight genera of Chitinozoa are described, of which six species are new, and thirty-four forms of scolecodonts are described. Of these, fifteen have not been described previously, but they are not named formally because in most cases each of these “species” is represented by only one specimen