Llandoverian and early Wenlockian Chitinozoa from southern Ohio and northern Kentucky, U.S.A.

Information about Silurian Chitinozoa from stratigraphic sampled sections in the United States is very scanty. To assess the stratigraphic significance of Silurian chitinozoans, 70 samples from 5 sections in southern Ohio and northern Kentucky were selected. About two‐thirds of the samples analyzed yielded chitinozoans, and most of these contained diagnostic assemblages. A total of 13 species have been identified. On the whole, the chitinozoans show close similarity to those from Baltoscandia and are less similar to faunas from, for instance, Anticosti Island, Spain, and North Africa. Chitinozoans with restricted ranges suggest correlation in agreement with those indicated by graptolites, conodonts and other fossils. The chitinozoans are most diverse and abundant in subtidal rocks, while intertidal rocks contain few and mostly planktic taxa. The water depth was an important ecological factor, but also other controlling factors were involved. The study has confirmed that the chitinozoans have great stratigraphie potential as index fossils in the Early Silurian of the Midcontinent United States.