''Entomaspis'' is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

of harpetid

trilobite Trilobites (; meaning "three lobes") are extinct marine arthropods that form the class Trilobita. Trilobites form one of the earliest-known groups of arthropods. The first appearance of trilobites in the fossil record defines the base of the ...

from Upper Cambrian to Early

Ordovician The Ordovician ( ) is a geologic period and system, the second of six periods of the Paleozoic Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period million years ago (Mya) to the start of the Silurian Period Mya. T ...

marine strata of the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territori ...

. Species are typified by their proportionally large, vaulted, croissant-shaped or bonnet-shaped cephalons that have the cheeks freed to become elongated, curved librigenial spines, and by their comparatively large, crescent-shaped eyes (in comparison with other eyed harpetids).

Species

''E. bridgei''

''E. bridgei'' is a species found in marine strata of

Missouri Missouri is a state in the Midwestern region of the United States. Ranking 21st in land area, it is bordered by eight states (tied for the most with Tennessee): Iowa to the north, Illinois, Kentucky and Tennessee to the east, Arkansas t ...

''E. clarki''

''E. clarki'' is a species found in Lower Ordovician marine strata of

Vermont Vermont () is a state in the northeast New England region of the United States. Vermont is bordered by the states of Massachusetts to the south, New Hampshire to the east, and New York to the west, and the Canadian province of Quebec to ...

.Shaw, Alan B. "Paleontology of Northwestern Vermont. XII. Fossils from the Ordovician Highgate Formation." Journal of Paleontology (1966): 1312-1330.

''E. radiata''

''E. radiata'' is the type species, and is found in Uppermost Cambrian and Lowermost Ordovician marine strata of Utah. It coexisted sympatrically with '' E. rawi''.

''E. rawi''

''E. rawi'' was originally described as ''Hypothetica rawi'', and coexisted with ''E. radiata'' in Lowermost Ordovician marine strata of Utah.

References

Sources

Trilobite info (Sam Gon III)''

External links

'' Trilobite info (Sam Gon III)''
Harpetida Cambrian trilobites Ordovician trilobites Fossils of the United States {{harpetida-stub Ordovician genus extinctions