English: Flexicalymene meeki (Foerste, 1910) - weathered, enrolled fossil trilobite from the Ordovician of the Cincinnati area, USA.

This fossil is from the famous Cincinnatian Series of the tristate area of Ohio-Kentucky-Indiana. Rocks in the Cincinnatian were deposited in relatively shallow marine facies during the Late Ordovician. The Cincinnatian succession is mostly interbedded limestones and shales. Most of the limestones are event beds (= tempestites), deposited during ancient storms.

The specimen is a partially complete enrolled trilobite, which is an extinct marine arthropod. Trilobites first appear in Lower Cambrian rocks and the entire group went extinct at the end of the Permian. They had a calcitic exoskeleton and nonmineralizing parts underneath (legs, gills, gut, etc.). The calcite skeleton is most commonly preserved in the fossil record, although soft-part preservation is known in some trilobites (Examples: Burgess Shale and Hunsruck Slate). Trilobites had a head (cephalon), a body of many segments (thorax), and a tail (pygidium). Molts and carcasses usually fell apart quickly - most trilobite fossils are isolated parts of the head (cranidium and free cheeks), individual thoracic segments, or isolated pygidia. The name "trilobite" was introduced in 1771 by Johann Ernst Immanuel Walch and refers to the tripartite division of the trilobite body - it has a central axial lobe that runs longitudinally from the head to the tail, plus two side lobes (pleural lobes).

The specimen is enrolled - many trilobites could roll up like modern terrestrial isopods (see: www.flickr.com/photos/vicbao/3417810096/in/photostream/li...). This was usually in response to being buried in sediments - often by storm events.

Classification: Animalia, Arthropoda, Trilobita, Polymerida, Calymenidae

Stratigraphy: float from the Richmondian Stage, upper Cincinnatian Series, upper Upper Ordovician

Locality: unrecorded site in the Cincinnatian outcrop belt of southwestern Ohio-southeastern Indiana-northern Kentucky, USA (probably southwestern Ohio)