''Entomaspis'' is an extinct

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of harpetid

trilobite Trilobites (; meaning "three-lobed entities") are extinction, extinct marine arthropods that form the class (biology), class Trilobita. One of the earliest groups of arthropods to appear in the fossil record, trilobites were among the most succ ...

from Upper

Cambrian The Cambrian ( ) is the first geological period of the Paleozoic Era, and the Phanerozoic Eon. The Cambrian lasted 51.95 million years from the end of the preceding Ediacaran period 538.8 Ma (million years ago) to the beginning of the Ordov ...

to Early

Ordovician The Ordovician ( ) is a geologic period and System (geology), system, the second of six periods of the Paleozoic Era (geology), Era, and the second of twelve periods of the Phanerozoic Eon (geology), Eon. The Ordovician spans 41.6 million years f ...

marine strata of the

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

. 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 (''see #Etymology and pronunciation, pronunciation'') is a U.S. state, state in the Midwestern United States, Midwestern region of the United States. Ranking List of U.S. states and territories by area, 21st in land area, it border ...

''E. clarki''

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

Vermont Vermont () is a U.S. state, state in the New England region of the Northeastern United States. It borders Massachusetts to the south, New Hampshire to the east, New York (state), New York to the west, and the Provinces and territories of Ca ...

.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 Ordovician genus extinctions Trilobite genera {{harpetida-stub