Agnostus, is a genus of agnostid trilobite belonging to the Family Agnostidae, that lived during the late Middle Cambrian – early Upper Cambrian. It is the type genus of the family Agnostidae and is subdivided into two subgenera, Agnostus and Homagnostus.
Bolboparia is an extinct genus of eodiscinid agnostid trilobites. It lived during the late Lower Cambrian in what today Canada and the United States.
Yunnanocephalus is a genus of ptychopariid trilobite. It lived during the late Atdabanian and Botomian stages, in what are currently Antarctica, Australia and China. It was a "moderately common" member of the Chengjiang Fauna. Yunnanocephalus is the only genus currently assigned to the Yunnanocephalidae family.
Exigua is an extinct genus from a well-known class of fossil marine arthropods, the trilobites. It lived from 501 to 497 million years ago during the Dresbachian faunal stage of the late Cambrian Period. Exigua is only known from the central part of the headshield or cranidium, so free cheeks, thorax and pygidium are unknown.
Weeksina is a genus of trilobites, an extinct group of marine arthropods. It lived during the Dresbachian faunal stage of the late Cambrian Period which lasted from 501 to 490 million years ago. Its calcified dorsal exoskeleton has an inverted egg-shape. Characteristics of this trilobite are the backward directed spine on the 8th of 10 segment of the articulated middle part of the body, and the second pair of furrows from the back on the raised central part of the headshield called glabella, which curve from inward to fully backward, almost isolating a pair of lobes, just in front of the occipital ring, that is defined by a furrow that crosses the entire width of the glabella. Weeksina is known only from the Weeks Formation at North Canyon, House Range, Millard County, Utah.
Meteoraspis is an extinct genus of ptychopariid trilobites of the family Tricrepicephalidae. The various species lived from 501 to 490 million years ago during the Dresbachian faunal stage of the late Cambrian Period. Fossils of Meteoraspis are characteristic of Late Cambrian strata in North America, though they are found in Late Cambrian strata elsewhere in the world, such as M. nevensis from Victoria Land, Antarctica.
Asaphiscus is a genus of trilobite that lived in the Cambrian. Its remains have been found in Australia and North America, especially in Utah.
Lonchodomas is a genus of trilobites, that lived during the Ordovician. It was eyeless, like all raphiophorids, and had a long straight sword-like frontal spine, that gradually transforms into the relatively long glabella. Both the glabellar spine and the backward directed genal spines are subquadrate in section. Lonchodomas has five thorax segments and the pleural area of the pygidium has two narrow furrows. Lonchodomas occurred in what are today Argentina, Canada (Newfoundland), Estonia, Latvia, Norway, Sweden, the Russian Federation and the United States.
Aulacopleura is a genus of proetid trilobite that lived from the Middle Ordovician to the Middle Devonian. Some authors may classify this group as subgenus Otarion (Aulacopleura). The cephalon is semicircular or semielliptical, with border and preglabellar field. The glabella is short, with or without defined eye ridges connecting it with eyes of variable size. Spines at the rear outer corners of the cephalon are present, typically reaching back to the 2nd to 4th thorax segment. The 'palate' is not connected to the dorsal shield of the cephalon. The cephalon is pitted, or has small tubercles. The thorax has up to 22 segments. The pleural ends are usually rounded. The pygidium is small (micropygous), with an even margin. A. koninckii had a modern type of compound eye.
Ellipsocephalus Zenker, 1833, is a genus of blind Cambrian trilobite, comprising benthic species inhabiting deep, poorly lit or aphotic habitats. E. hoffi is a common trilobite mainly from central Europe.
The Cambrian Warrior Formation is a mapped limestone bedrock unit in Pennsylvania.
Acmarhachis is a genus of trilobite in the order Agnostida, which lived in what are now Australia, Canada, China (Anhui), Kazakhstan, Russia (Kharaulakh), and the US. It was described by Resser in 1938, and the type species is Acmarhachis typicalis.
Phalagnostus is a genus of small trilobites, in the order Agnostida. It lived during the Middle Cambrian, in what are now Canada, China, the Czech Republic, Denmark, England, France, the Russian Federation, Wales, Sweden, and possibly the United States (Vermont). The headshield is almost entirely effaced and wider than the tailshield. The pygidium is also very effaced, but the ovate pygidial axis is well defined and a border furrow is also present.
Thoracocare is a minute to very small trilobite, that lived during part of the Middle Cambrian in what are today the states of Idaho, Nevada and Utah. It is the only trilobite known with just two thorax segments outside most members of the Agnostida order. It can be distinguished from Agnostida by the very wide subquadrate glabella, parallel-side or widening forward in the largest specimen, with the full front side touching the border. Two species are known, one, T. idahoensis, only from pygidia.
Delgadella is a diminutive trilobite that lived during the late Lower Cambrian and has been found in Russia, Mongolia, Spain, Italy (Sardinia), Portugal, Morocco and Canada (Newfoundland). It can be recognized by its strongly effaced headshield and tailshield, with narrow but distinct furrows and borders along its margins, and three thorax segments.
Toragnostus is a genus of trilobites restricted to the late Middle Cambrian. Its remains have been found in the United States, Greenland, Denmark, China, Sweden, the Russian Federation, and Kazakhstan. Its headshield and tailshield are almost completely effaced and it has two thorax segments.
Cedaria is a small, rather flat trilobite with an oval outline, a headshield and tailshield of approximately the same size, 7 articulating segments in the middle part of the body and spines at the back edges of the headshield 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.
Kendallina is a genus of trilobite with an inverted egg-shaped outline, a wide headshield, small eyes, small deflected spines, 12 thorax segments and a small, short tailshield. It lived during the Upper Cambrian in what are today Canada and the United States.
Orygmaspis is a genus of asaphid trilobite with an inverted egg-shaped outline, a wide headshield, small eyes, long genal spines, 12 spined thorax segments and a small, short tailshield, with four pairs of spines. It lived during the Upper Cambrian in what are today Canada and the United States.
Tricrepicephalus is an extinct genus of ptychopariid trilobites of the family Tricrepicephalidae with species of average size. Its species lived from 501 to 490 million years ago during the Dresbachian faunal stage of the late Cambrian Period. Fossils of Tricrepicephalus are widespread in Late Cambrian deposits in North America, but is also known from one location in South-America. Tricrepicephalus has an inverted egg-shaped exoskeleton, with three characteristic pits in the fold that parallels the margin of the headshield just in front of the central raised area. The articulating middle part of the body has 12 segments and the tailshield carries two long, tubular, curved pygidial spines that are reminiscent of earwig's pincers that rise backwards from the plain of the body at approximately 30°.
