Mcnamaraspis kaprios is an arthrodiran placoderm of the Family Plourdosteidae that inhabited the ancient reef system of north Western Australia

Western Australia

Western Australia is a state of Australia, occupying the entire western third of the Australian continent. It is bounded by the Indian Ocean to the north and west, the Great Australian Bight and Indian Ocean to the south, the Northern Territory to the north-east and South Australia to the south-east...

 during the Late Devonian period (c. 380-375 million years ago). The type specimen was found and described by John A. Long from the Gogo Formation

Gogo Formation

The Gogo Formation in the Kimberley region of Western Australia is a Lagerstätte that exhibits exceptional preservation of a Devonian reef community.- Sedimentology :...

 near Fitzroy Crossing. This fossil fish showed new anatomical features in arthrodires, like the well-preserved annular cartilages of the snout, previously inferred to be present by Erik Stensiö

Erik Stensiö

Erik Helge Osvald Stensiö was a Swedish paleozoologist.Erik Andersson, as his original name was, was born in the village of Stensjö in Döderhult parish in Kalmar County; he later took his new surname from his place of origin and is occasionally referred to with both names...

of Sweden.

On December 5th, 1995, Mcnamaraspis kaprios was officially proclaimed as the State Fossil emblem of Western Australia by the Governor of Western Australia, thus becoming the first official state fossil emblem for any state of Australia.