1.55" Flexicalymene Trilobite with Pyrite - Ohio

This is a large, prone specimen of Flexicalymene retorsa from the famous trilobite locality at Mt. Orab, Ohio. At 1.55" long this is the top few percent size wise for these trilobites and it's nicely inflated and prepared using air abrasives. Another cool feature to this specimen are the small pyrite crystals that have formed on the exterior of the trilobite.

Flexicalymene is a genus of trilobites of the order Phacopida, suborder Calymenina. These ancient arthropods are an index fossil of the Ordovician (488-443 mya). The graceful articulation, especially of the thorax segments, demonstrates that this distant precursor of insects is deserving of its delightful name.

Flexicalymene is often found enrolled, seemingly to protect its softer underside from threats on a sea floor teeming with ancient life and increasingly complex predators. Sealing itself inside the hard carapace may be a protective maneuver, or it may simply be the pose of death.

There are two species of Flexicalymene found in the Richmond Formation but in different sub-units. Flexicalymene meeki have small genal spines and is the more common of the two, often coming from Mt Orab, Ohio. These spines are absent in F. retrorsa. The F. retrorsa cephalon is more rounded, while the F. meeki cephalon is pronounced. They were also denizens at different locales. Calymene, meaning “beautiful crescent”, should not be confused with Flexicalymene. It is a separate genus.

Flexicalymene meeki has been studied for its abundant perforations. The perforations have been interpreted as the loci of sensory hairs. These loci occur in many sizes, and are an interesting feature of exoskeleton microfeatures. They are concentrated on those areas likely to contact other objects in the environment.
DETAILS
SPECIES
Flexicalymene retorsa
LOCATION
Mt. Orab, Ohio
FORMATION
Arnheim Formation
SIZE
1.55" long on 3.4x2.4" matrix
SUB CATEGORY
ITEM
#72027
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