Asaphiscus

Asaphiscus is a genus of trilobite that lived in the Cambrian. Its remains have been found in Australia and North America, especially in Utah.

Asaphiscus wheeleri, 37mm long

Asaphiscus
Temporal range: 510–499 Ma Middle Cambrian
Asaphiscus wheeleri, Cambrian shale, Utah
Scientific classification
Kingdom:
Animalia
Phylum:
Arthropoda
Class:
Trilobita
Order:
Ptychopariida
Family:
Asaphiscidae
Genus:
Asaphiscus

Meek, 1873
Species
Synonyms

Eteraspis

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;[1] and Menevian, Wheeler Formation, House Range, Utah, 39.2° N, 113.3° W).[2]

Description

Asaphiscus are average size trilobites of (up to 8 centimetres or 3.1 inches) with a rather flat calcified dorsal exoskeleton of inverted egg-shaped outline, about 1½× longer than wide, with the widest point near the back of the headshield (or cephalon). 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 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) has 7-11 segments (9 in A. wheeleri), with rounded tips. The tailshield (or pygidium) is about 30% of the body length, is semi-circular in shape, with a wide flat border, and an entire margin.[3]

Reassigned species

Some species originally described as belonging to Asaphiscus have later been reassigned to other genera.[4]

Sources
  • A Pictorial Guide to Fossils by Gerard Ramon Case

References
  1. Conway Morris, S.; Robison, R.A. (1986). "Middle Cambrian priapulids and other soft-bodied fossils from Utah and Spain". University of Kansas Paleontological Contributions. 117: 1–22. cited on Paul Hearn. "Lower Wheeler Shale". Fossilworks. Retrieved 2015-01-16.
  2. Robison, R.A. (1971). "Additional Middle Cambrian trilobites from the Wheeler Shale of Utah". Journal of Paleontology. 45 (5): 796–804. cited on Shenan Peeters. "Wheeler Formation, House Range, Utah". Fossilworks. Retrieved 2015-01-16.
  3. Moore, R.C. (1959). Arthropoda I - Arthropoda General Features, Proarthropoda, Euarthropoda General Features, Trilobitomorpha. Treatise on Invertebrate Paleontology. Part O. Boulder, Colorado/Lawrence, Kansas: Geological Society of America/University of Kansas Press. pp. O290–O291. ISBN 0-8137-3015-5.
  4. Peters, S.E. (2003). "Paleontology and taphonomy of the Upper Weeks Formation (Cambrian, Upper Marjuman, Cedaria Zone) of western Utah" (PDF). Unpublished PhD dissertation. University of Chicago.
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