Naraoia

Naraoia Temporal range: Cambrian
Naraoia spinosa
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	†Trilobita
Order:	Nectaspida
Family:	Naraoiidae
Genus:	Naraoia Walcott, 1912
Type species
N. compacta
Species
N. compacta Walcott, 1912 N. spinifer Walcott 1931 N. spinosa Zhang & Hou, 1985 N. halia Simonetta & Delle Cave 1975 N. pammon Simonetta & Delle Cave 1975

An fossil specimen of Naraoia walcott on display at the Paleozoological Museum of China.

Naraoia is a genus of trilobites (or trilobite-like arthropods) found in Cambrian strata of the Burgess Shale and the Maotianshan shales Lagerstätte. They were flattened, oval-shaped animals, with an uncalcified shield that was divided into two regions, a smaller region covering the head, and a larger section covering the body. There are no hint of lobes, as in true trilobites. All species were blind, showing no trace of eyes.

Naraoia fossils range between 2 and 4 centimetres in length. 392 specimens of Naraoia are known from the Greater Phyllopod bed, where they comprise 0.74% of the community.^[1]

The name is derived from Narao, the name of a group of small lakes in Cataract Brook canyon, above Hector on the Canadian Pacific Railway, British Columbia, Canada."^[2]

Classification

When the fossil was first discovered in Canada's Burgess Shale, it was believed to be a crustacean, such was the difference between this and other trilobites. Its continuous shield hid most of its structure, interfering with proper classification. When Harry B. Whittington began dissecting some specimens (Naraoia was among the most populous of the Burgess Shale animals), he discovered that the legs (and gills) of the beasts were very similar, if not identical to those of trilobites, thus the current placement of Naraoia in Class Trilobita.

Related Fossil Species

Misszhouia longicaudata was initially placed with Naraoia, but was later assigned to its current genus.[1]

References

1. ^ Caron, J. -B.; Jackson, D. A. (October 2006). "Taphonomy of the Greater Phyllopod Bed community, Burgess Shale". PALAIOS 21 (5): 451–465. doi:10.2110/palo.2003.P05-070R.  edit
2. ^ Charles D. Walcott, "Middle Cambrian Branchiopoda, Malacostraca, Trilobita, and Merostomata," in Cambrian Geology and Paleontology II (Smithsonian, 1914), p. 175.

The Smithsonian Intstitution's Naraoia page

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