Trilobite Death Assemblage from Middle Cambrian of Utah

Name: Modocia sp. (brevispina?); Agnostida (sp indet)

Class Trilobita, Order Ptychopariida, Family Marjumiidae & Order Agnostida

Geological Time: Middle Cambrian

Size: Modocia: 17 mm long and 12 mm wide, 7 mm long and 5 mm wide Agnostids: 2-8 mm long

Location: House Range, Marjum Formation, Millard County, Utah

Description: Coming from the Cambrian Marjum Formation deposits of Millard County, Utah this is a fine association plaque of two trilobites of quite disparate morphology. The larger trilobite is an example of the genus Modocia. A second smaller example missing the librigenae is also present. There are also over THIRT Y2- 8 mm examples of an agnostid trilobite . The members of the Agnostida are mostly thought to have been planktonic in nature. Most are blind, and have a pygidium equal in size to the cephalon (ispopygous), making it hard to tell which end was which! This large plaque makes an excellent display specimen of a death assemblage of finely-preserved Middle Cambrian trilobites of Utah.

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