Trilobites are extinct marine arthropods that form the class Trilobita. Trilobites form one of the earliest known groups of arthropods. The first appearance of trilobites in the fossil record defines the base of the Atdabanian stage of the Early Cambrian period and they flourished throughout the lower Paleozoic before slipping into a long decline, when, during the Devonian, all trilobite orders except the Proetida died out. The last extant trilobites finally disappeared in the mass extinction at the end of the Permian about 252 million years ago. Trilobites were among the most successful of all early animals, existing in oceans for almost 270 million years, with over 22,000 species having been described.
Phacopidae is a family of phacopid trilobites that ranges from the Lower Ordovician to the Upper Devonian, with representatives in all paleocontinents.
Phacops is a genus of trilobites in the order Phacopida, family Phacopidae, that lived in Europe, northwestern Africa, North and South America and China from the Late Ordovician until the very end of the Devonian, with a broader time range described from the Late Ordovician. It was a rounded animal, with a globose head and large eyes, and probably fed on detritus. Phacops is often found rolled up ("volvation"), a biological defense mechanism that is widespread among smaller trilobites but further perfected in this genus.
Calymene Brongniart, 1822, is a genus of trilobites in the order Phacopida, suborder Calymenina, that are found throughout North America, North Africa, and Europe in primarily Silurian outcrops. Calymene is closely related to Flexicalymene, and both genera are frequently found enrolled. Calymene trilobites are small, typically 2 cm in length. The cephalon is the widest part of the animal and the thorax usually has 13 segments.
Eophacops is a genus of trilobites from the order Phacopida, family Phacopidae. These trilobites lived during the Middle Silurian in what now are North America and North-West Europe. Species assigned to this genus can be distinguished from Phacops by their small size (2–3 cm). Eophacops has very large eyes compared to the rest of its body.
Olenoides was a trilobite from the Cambrian period. Its fossils are found well-preserved in the Burgess Shale in Canada. It grew up to 10 cm long.
Naraoia is a genus of small to average size marine arthropods within the family Naraoiidae, that lived from the early Cambrian to the late Silurian period. The species are characterized by a large alimentary system and sideways oriented antennas.
Asaphus is a genus of trilobites that is known from the Lower and Middle Ordovician of northwestern Europe.
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.
Crepicephalus is an extinct genus from a well-known class of fossil marine arthropods, the trilobites. It lived from 501 to 490 million years ago during the Dresbachian faunal stage of the late Cambrian Period.
Asaphiscus is a genus of trilobite that lived in the Cambrian. Its remains have been found in Australia and North America, especially in Utah.
Acastoides is an extinct genus of trilobite that lived during the Silurian and Devonian. It has been found in Bolivia, France, Morocco, Poland, Turkey and the United Kingdom.
Dienstina is a trilobite in the order Phacopida, that existed during the lower Devonian in what is now Germany. It was described by Richter and Richter in 1931, and the type species is Dienstina diensti, which the authors had originally assigned to the genus Phacopidella in 1923. The type locality was in Oberscheld, Rhenish Massif.
Acastocephala is a genus of trilobite from the middle Silurian, known from the United Kingdom.
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.
Battus is a synonym for several agnostid trilobites, now assigned to other genera.
TrilobitesLink, 1807 is a disused genus of trilobites, the species of which are now all assigned to other genera.
ConocephalitesBarrande, 1852, is a disused name for a genus of trilobite, of which the species have now been reassigned to other genera. The name was introduced as a replacement for ConocephalusZenker, 1833, which was unavailable since Thunberg used it in 1815 for a genus of conehead bushcricket. Barrande however was unaware that Conocoryphe had already been proposed by Hawle and Corda in 1847.
ArionellusBarrande, 1850, is a disused name for a genus of trilobite. The name Arionellus was a replacement for ArionidesBarrande, 1847, itself a replacement for ArionBarrande, 1846, which was preoccupied because Férussac had already used it in 1819 for a genus of slugs.
Entomaspis is an extinct genus of harpetid trilobite from Upper Cambrian to Early Ordovician marine strata of the United States. Species are typified by their proportionally large, vaulted, croissant-shaped or bonnet-shaped cephalons that have the cheeks freed to become elongated, curved librigenial spines, and by their comparatively large, crescent-shaped eyes.
