Description: Internal cast of an abundant fossil in the Cincinnati area, a Nautiloid Cephalopod. There are a number of similar genera, even families, of these cephalopods, and they cannot be identified by their external characteristics. The similarity of these genera, and tradition, has led many collectors to the unfortunate habit of calling them all "Orthoceras". "Orthoceras" as a generic name of a cephalopod is invalid and should be abandoned. True ID is possible only by thin-section analysis. The straight shell-form is called an "orthocone". Some of these animals reached 12 feet in length.

Age: Upper Ordovician (Cincinnatian).

Found By: pamela.

Location Found: Milford, Ohio.

Current Custodian: pamela.

Identified By: hemipristis.

References: University of Georgia Stratigraphy Lab - Cephalopod page