Flexicalymene is a genus of trilobites of the order Phacopida

Phacopida

Phacopida is an order of trilobite that lived from the Ordovician to the Devonian. It is made up of a morphologically diverse group of related suborders....

, suborder Calymenina

Calymenina

Calymenina is a suborder of the trilobite order Phacopida....

. They are found abundantly in North America. Flexicalymene specimens can be mistaken for Calymene

Calymene

Calymene is a genus of trilobites in the order Phacopida that were found throughout North America, North Africa, and Europe in primarily Silurian outcrops. Calymene are easily confused with Gravicalymene and Flexicalymene, also part of the Calymenidae family...

, Gravicalymene

Gravicalymene

Gravicalymene is a genus of trilobites from the order Phacopida, suborder Calymenia. Gravicalymene has been a 'hot button' trilobite lately. The species that are currently in this genus have been in Calymene and Sthenocalymene...

, Diacalymene

Diacalymene

Diacalymene is a genus of trilobite from the order Phacopida, suborder Calymenina. It includes the species D. ouzregui, D. clavicula, D. diademata and D. gabrielsi. It lived in the Ordovician and Silurian periods....

and a few other Calymenina

Calymenina

Calymenina is a suborder of the trilobite order Phacopida....

 genera. They are used as an index fossil in the Ordovician

Ordovician

The Ordovician is a geologic period and system, the second of six of the Paleozoic Era, and covers the time between 488.3±1.7 to 443.7±1.5 million years ago . It follows the Cambrian Period and is followed by the Silurian Period...

. Ohio and
North America are particularly known for being rich with Flexicalymene fossils. Species include F. meeki and F. retrorsa (Ohio, Kentucky and Indiana), F. granulosa (Ohio, Kentucky and Quebec), F. senaria (Quebec) and F. croneisi (Ontario).
Flexicalymene fossils can be found at an age of 95–110 mya.