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 Temporal range: 516–498 Ma PreꞒ Ꞓ O S D C P T J K Pg N Middle Cambrian
Asaphiscus wheeleri, Cambrian shale, Utah
Scientific 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

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 1+1⁄2× 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 1⁄8× 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 1⁄8× 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]

• 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