Trace fossils of the Cincinnati Area

All previously described "fucoids" (fossil seaweeds) from the North American standard section for the Upper Ordovician are discussed and evaluated. A restudy of type materials reveals that approximately one-fourth of these are inorganic sedimentary markings, while the remainder are trace fossils (tracks, trails, burrows). Extensive treatment is given to the early history of trace fossil studies, generic and suprageneric classification, and preservation of trace fossils. Thirty genera and 44 species of Cincinnatian traces are illustrated and interpreted. These are grouped in the five categories proposed by Seilacher (1953b). New genera proposed include Altocotichnus, the trail of a large arthropod; Fascifodina, a bundled feeding burrow; and Tylichnus, a trail of unknown origin. In addition, a new species of the trilobite burrow Rusophycus is established under the name R. crypiolithi. It represents the first known burrow of a trinucleid. A comparison of the entire Cincinnatian trace fossil community with assemblages from different ages and locations reveals a correlation between the types of trace fossils and the general environmental setting.