Middle Cambrian Trilobite Death Assemblage from House Range

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

Class Trilobita, Order: Ptychopariida, Family Marjumiidae & Order Agnostida

Geological Age: Middle Cambrian

Size: Modocia: 17 mm long and 12 mm wide, 7 mm long and 5 mm wide Agnostids: 2-8 mm long on a 200 mm by 118 mm matrix

Fossil Locality: House Range, Marjum Formation, Millard County, Utah

Cambrian Trilobite Death AssemblageDescription: Coming from the Cambrian Marjum Formation deposits of Millard County, Utah this is a fine association plaque of two trilobites of quite disparate morphology. Marjum Formation trilobitesThe larger trilobite is an example of the genus Modocia. A second smaller example missing the librigenae is also present. There are also over THIRTY, 2- 8 mm trilobites of order Agnostida. Members of the Agnostida are often found in mass mortality in the various House Range Cambrian strata, and often in association with trilobites of other orders, particularly the Ptychopariids. Most agnostids are blind trilobites, and have a pygidium essentially equal in size to the cephalon (ispopygous), making it hard to tell which end was which.

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