Asaphiscus
Temporal range: Middle Cambrian
Asaphiscus wheeleri, Cambrian shale, Utah
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Class: †Trilobita
Order: †Ptychopariida
Family: †Asaphiscidae
Genus: †Asaphiscus
Meek, 1873
Type species
Asaphiscus wheeleri
Meek, 1873
Species
  • A. wheeleri Meek, 1873
  • A. laeviceps Walcott, 1884
    Synonyms: Ptychoparia laeviceps, Eteraspis laeviceps
Synonyms

Eteraspis Resser, 1935

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

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 wheeleri, 37 mm long

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 17 December 2021.
  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 17 December 2021.
  3. ↑ Moore, R.C. (1959). Arthropoda I - Arthropoda General Features, Proarthropoda, Euarthropoda General Features, Trilobitomorpha. Treatise on Invertebrate Paleontology. Vol. 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. Archived from the original (PDF) on February 26, 2014.
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