Cephalitic spine

2012-Nov30-AmpyxThis is the spine on the front of the trilobite Ampyx linleyensis.  It is an extension of the cephalon and probably contained sensory organs for detecting food organisms in soft marine mud.  May trilobites that were sea bottom dwellers has long forward pointing spines.

2012-Nov30a-CnemidopygeThis spine is  projecting forward from a specimen of Cnemidopyge bisecta.  Often these delicate spines are not seen, or preserved as traces in the matrix.  occasionally a specimen will be found where the spines are fully preserved.

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Phacops


The compound eye of the trilobite Phacops logani seen here has lots of lenses visible on the surface.  This fossil shows a slight dimpling in the middle of each lens which may be a post-mortem artifact caused by the lens surfaces collapsing after the shedding of this carapace.

This specimen of the same species shows a broken eye on a preserved whole specimen.  The shape of the light canals can be seen near the base of the eye where the upper part of the eye structure has been sliced off during excavation of the fossil.

Pedinopariops

Pedinopariops brongniarti has a distinct type of eye structure.  This trilobite shows a compound eye with lots of lens elements preserved in lateral view.  If the specimen is viewed dorsally, the top of the eye structure has no lenses.

It appears that this animal could only see sideways, suggesting that it was probably able to float close to the sea surface and watch for predators approaching from the same level.  This Middle Devonian species is commonly found enrolled, within the Ahrdorf formation in Germany.

Kloucekia

This small trilobite carapace is 4mm wide.  It is identified as Kloucekia micheli from the Llanvirn.  This species is also known as Phascopidina micheli by some authors.  It is quite a rare trilobite with a large geographical range.

Pricyclopyge

Preserved on fine varved silts from a lake deposit is a slightly distorted specimen of Pricyclopyge binodosa.  This specimen is from Shropshire, UK and is a Llanvern species with particularly large and fine eyes.

A close image shows the poor quality of the preservation on this specimen, but the eye is visible as a slight bulge on the cephalon margin.

Homotelus

 

From Carter County, Oklahoma, USA, comes this specimen of Homotelus bromidensis.  It is named from the Bromide Formation of the Middle Ordovician.  Like many Asaphid Trilobites it has a cephalon and pygidium of roughly equal size and shape.

Diephon

This tiny Cherurid trilobite is Diephon barrandei. This is an unusual Silurian trilobite with a spherical cephalon and an unusual forked pygidium.  It is supposed that the cephalon may have been oil filled to give the trilobite buoyancy control.  Some specimens show long antennae emanating from the junction of the glabella and the lateral cheek spines.