''Asaphiscus'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

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 At ...

that lived in the

Cambrian The Cambrian Period ( ; sometimes symbolized C with bar, Ꞓ) was the first geological period of the Paleozoic Era, and of the Phanerozoic Eon. The Cambrian lasted 53.4 million years from the end of the preceding Ediacaran Period 538.8 million ...

. Its remains have been found in

Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

and

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...

, especially in

Utah Utah ( , ) is a state in the Mountain West subregion of the Western United States. Utah is a landlocked U.S. state bordered to its east by Colorado, to its northeast by Wyoming, to its north by Idaho, to its south by Arizona, and to it ...

Distribution

* A. wheeleri'' occurs in the Middle Cambrian of the United States (Delamaran, Lower Wheeler Shale, Millard County, Utah, 40.0°N, 113.0°W; and Menevian, Wheeler Formation, House Range, Utah, 39.2° N, 113.3° W).

Description

''Asaphiscus'' are average size trilobites of (up to ) with a rather flat calcified

dorsal Dorsal (from Latin ''dorsum'' ‘back’) may refer to: * Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism * Dorsal, positioned on top of an aircraft's fuselage * Dorsal co ...

exoskeleton An exoskeleton (from Greek ''éxō'' "outer" and ''skeletós'' "skeleton") is an external skeleton that supports and protects an animal's body, in contrast to an internal skeleton (endoskeleton) in for example, a human. In usage, some of the ...

of inverted egg-shaped outline, about 1½× longer than wide, with the widest point near the back of the headshield (or

cephalon Cephalon, Inc. was an American biopharmaceutical company co-founded in 1987 by pharmacologist Frank Baldino, Jr., neuroscientist Michael Lewis, and organic chemist James C. Kauer—all three former scientists with the DuPont Company. Baldino s ...

). The cephalon is about 40% of the body length, is semi-circular in shape, has wide rounded genal angles, and a well defined border of about ⅛× the length of the cephalon. The central raised area of the cephalon (or

glabella The glabella, in humans, is the area of skin between the eyebrows and above the nose. The term also refers to the underlying bone that is slightly depressed, and joins the two brow ridges. It is a cephalometric landmark that is just superior to ...

is conical in outline with a wide rounded front and is separated from the border by a preglabellar field of about ⅛× the length of the cephalon, and has 3 sets of furrows that may be clear or inconspicuous. The articulated middle part of the body (or

thorax The thorax or chest is a part of the anatomy of humans, mammals, and other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main divisions of the cre ...

) has 7-11 segments (9 in ''A. wheeleri''), with rounded tips. The tailshield (or

pygidium The pygidium (plural pygidia) is the posterior body part or shield of crustaceans and some other arthropods, such as insects and the extinct trilobites. In groups other than insects, it contains the anus and, in females, the ovipositor. It is compo ...

) is about 30% of the body length, is semi-circular in shape, with a wide flat border, and an entire margin.

Reassigned species

Some species originally described as belonging to ''Asaphiscus'' have later been reassigned to other genera. * ''A. capella'' = '' Glyphaspis capella'' * ''A. granulatus'' = '' Genevievella granulata'' * ''A. gregarius'' = '' Blainia gregarius'' * ''A. minor'' = '' Cedaria minor'' * ''A. unispinus'' = '' Weeksina unispina''

Sources

* ''A Pictorial Guide to Fossils'' by Gerard Ramon Case

References

External links

''Asaphiscus''
in the

Paleobiology Database The Paleobiology Database is an online resource for information on the distribution and classification of fossil animals, plants, and microorganisms. History The Paleobiology Database (PBDB) originated in the NCEAS-funded Phanerozoic Marine Pale ...

{{Taxonbar, from=Q4803579 Ptychoparioidea Ptychopariida genera Cambrian trilobites of Australia Cambrian trilobites of North America Fossils of Georgia (U.S. state) Wheeler Shale Cambrian genus extinctions