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Gogia spiralis (Robison, 1965)
Gogia is a Cambrian cystoid that is among the earliest and most primitive groups of echinoderms. For this reason they are sometimes called a "dawn crinoids". They had a vase-shaped body (calyx), covered by plates that were symmetrical and have a bifurcated brachiole, a slender arm-like structure for food-gathering that closely resembled those in cystoids. Gogia differed from true crinoids in that they had pores along the margins separating the plates, and the type of feeding arms they displayed. The species Gogia spiralis derives its name from its tightly spiraled arms and is only one of three Gogia species to have spiraled arms. Gogia had a vase-shaped body or calyx with irregularly positioned plates. It also had a stalk made up of smaller plates that attached to the sea floor, and food-gathering arm-like structures called brachioles. Gogia was a sessile (stationary) suspension feeder gathering food with its arms in calm waters of shallow Cambrian seas. Gogia spiralis usually attached directly to the mud, but on rare occasions attached to brachiopods and trilobite fragments on the sea floor. Gogia were widely distributed in the lower and middle Cambrian of western North America, but only a few partial specimens have been found in the Burgess Shale. Gogia occurred at the base of the cystoid radiation, with three distinct cystoid lineages derived from different Gogia species. Gogia lived only during the Cambrian time period, but the cystoids that evolved from them survived until the end of the Devonian.
Wheeler Shale Miaolingian USAywang21
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Elrathia kingi (Meek, 1870)
Elrathia is a genus of ptychopariid trilobite species that lived during the Middle Cambrian of Utah, and possibly British Columbia. E. kingii is one of the most common trilobite fossils in the USA locally found in extremely high concentrations within the Wheeler Formation in the U.S. state of Utah. E. kingii has been considered the most recognizable trilobite. Commercial quarries extract E. kingii in prolific numbers, with just one commercial collector estimating 1.5 million specimens extracted in a 20-year career. 1950 specimens of Elrathia are known from the Greater Phyllopod bed, where they comprise 3.7% of the community. Etymology - Even though the generic name Elrathia was first published in the combination E. kingii, a species from the House Range, Utah, the name, itself, is derived from Elrath, Cherokee County, Alabama. Description - E. kingii is a medium-sized trilobite with a smooth sub-ovate carapace that is tapered towards the rear. Thorax is usually 13 segments. Pygidium has four axial rings and a long terminal piece. Posterior margin of the pygidium has a long broad medial notch. In contrast, E. marjum usually has 12 segments, 5 axial rings, lacks a notched posterior margin and possess incipient antero-lateral spines. The British Columbian species, E. permulta, is much smaller, averaging about only 20 millimeters, and has up to thoracic 14 segments. Because E. permulta lacks several diagnostic features of the genus it may even represent a distinct genus. Synonyms - Elrathia is variously known as Elrathina, which is a separate genus sometimes considered to be a synonym of Ptychoparella. The species E. kingii is often erroneously called E. kingi (with one i).
Wheeler Shale Miaolingian USAywang21
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Asaphiscus wheeleri (Meek, 1873)
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 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. A Chinese trilobite Tenistion typicalis was used for scale.
Wheeler Shale Miaolingian USAywang21
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Cedaria minor (Walcott, 1916)
This trilobite is a member of the family Cedariidae known as Cedaria minor. Cedaria is a small, rather flat trilobite with an oval outline, a headshield and tail shield of approximately the same size, 7 articulating segments in the middle part of the body and spines at the back edges of the head shield that reach halflength of the body. Cedaria lived during the early part of the Upper Cambrian (Dresbachian), and is especially abundant in the Weeks Formation.
Weeks Upper Middle Cambrian, Cenomanian Stage USAywang21