Large, 3.35" Isoteloides - Fillmore Formation, Utah

This is a large, 3.35" Isoteloides trilobite from the Carolinites nevadensis Zone in the Fillmore Formation in Utah. It appears very similar to Isoteloides flexus found significantly higher in the formation, but every species in this zone has been described as different species from the higher zones, so I suspect this one would be also.

Despite missing it's left cheek it's the most complete, large specimen we've recovered since we started digging the layers in the Carolinites nevadensis Zone. There is some crack-fill, shell restoration, mostly on the tail of the trilobite, <5% in total.

Trilobites were a very diverse group of extinct marine arthropods. They first appeared in the fossil record in the Early Cambrian (521 million years ago) and went extinct during the Permian mass extinction (250 million years ago). They were one of the most successful of the early animals on our planet with over 25k described species, filling nearly every evolutionary niche. Due in large part to a hard exoskeleton (shell), they left a excellent fossil record.
Isoteloides aff. flexus
FossilEra Lease, Southern House Range, Utah
Fillmore Formation - Carolinites nevadensis Zone
3.35" long on 7.9x6" rock
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