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 20,000 species having been described.
John William Salter was an English naturalist, geologist, and palaeontologist.
Flexicalymene Shirley, 1936. is a genus of trilobites belonging to the order Phacopida, suborder Calymenina and Family Calymenidae. Flexicalymene specimens can be mistaken for Calymene, Gravicalymene, Diacalymene and a few other Calymenina genera. They are used as an index fossil in the Ordovician. Ohio and North America are particularly known for being rich with Flexicalymene fossils.
Acidiscus Rasetti, 1966, is a genus of Eodiscinid trilobite belonging to the family Weymouthiidae Kobayashi T. (1943), Order Agnostida Salter (1864). It lived during the Botomian stage = late Lower Cambrian Stage 4 ; the upper Botomian boundary corresponds to base of the Middle Cambrian, Miaolingian Series and Wuliuan stage.
Acimetopus Rasetti, 1966, is a genus of Eodiscinid trilobite belonging to the family Weymouthiidae Kobayashi (1943), Order Agnostida Salter (1864). It lived during the Botomian stage. = late Lower Cambrian Stage 4 ; the upper Botomian boundary corresponds to base of the Middle Cambrian, Miaolingian Series and Wuliuan stage.
Analox Rasetti, 1966 is a genus of Eodiscinid trilobites belonging to the family Weymouthiidae Kobayashi T. (1943), Order Agnostida It lived during the Botomian stage. It can easily be distinguished from other trilobites by the two furrows that extend forwards and sidewards from the front of the glabella.
Leptochilodiscus Rasetti, 1966 [= Kerberodiscus Bassett et al., 1976] is a genus of Lower Cambrian Eodiscinid trilobite belonging to the family Weymouthiidae Kobayashi (1943), Order Agnostida. It lived during the Botomian stage = late Lower Cambrian Stage 4 ; the upper Botomian Stage boundary corresponds to base of both the Middle Cambrian Wuliuan stage and Miaolingian Series.
Ninadiscus Korobov, 1980, is a genus of Eodiscinid trilobite belonging to the family Weymouthiidae Kobayashi (1943), Order Agnostida Salter (1864). It lived during the Botomian Stage = late Lower Cambrian Stage 4 ; the upper Botomian boundary corresponds to the base of the Middle Cambrian, the Miaolingian Series and Wuliuan Stage.
Stigmadiscus Rasetti, 1966, is a genus of Lower Cambrian Eodiscinid trilobite belonging to the family Weymouthiidae Kobayashi (1943) Order Agnostida It lived during the Botomian stage, = late Lower Cambrian Stage 4 ; the upper Botomian Stage boundary corresponds to base of both the Middle Cambrian Wuliuan stage and Miaolingian Series.
Chelediscus Rushton, 1966, is a genus of Eodiscinid trilobite belonging to the family Weymouthiidae Kobayashi T. (1943), Order Agnostida Salter (1864). The Treatise assigns this genus to the Calodiscidae; Cotton and Fortey (2005) however move it to the Weymouthiidae. Chelediscus lived during the later part of the Botomian stage.
Runcinodiscus Rushton is a genus of Lower Cambrian Eodiscinid trilobite belonging to the family Weymouthiidae, Order Agnostida.
Pagetia Walcott, 1916. is a small genus of trilobite, assigned to the Eodiscinid family Pagetiidae and which had global distribution during the Middle Cambrian. The genus contains 55 currently recognized species, each with limited spatial and temporal ranges.
Fritzolenellus is an extinct genus from a well-known class of fossil marine arthropods, the trilobites, with three known species. It lived during the early part of the Botomian stage, which lasted from approximately 524 to 518.5 million years ago. This faunal stage was part of the Cambrian Period. Fritzolenellus occurred in parts of the paleocontinent Laurentia in what are now Northwestern Canada, Northwestern Scotland, and North-Greenland.
Weymouthia is an extinct genus of eodiscinid agnostid trilobites, which lived at the end of the Lower Cambrian, in what are now the eastern United States, England, Siberia and China.
Mallagnostus Howell, 1935, is a trilobite genus belonging to the family Weymouthiidae Kobayashi T. (1943), Order Agnostida Salter (1864) according to Whittington et al. 1997. It lived during the late Lower Cambrian, with remains found in USA, Canada (Newfoundland), Spain, England, Russia, Mongolia, and the early Middle Cambrian as reported from China and Russia (Yakutia).
Tannudiscus Pokrovskaya (1959) is a genus of Eodiscinid trilobites belonging to the family Weymouthiidae Kobayashi T. (1943), Order Agnostida. It lived during the late Lower Cambrian, with remains found in Canada (Newfoundland), China (Gansu), The United Kingdom (England), and the Russian Federation.
Jinghediscus Xiang & Zhang, 1985 is a genus of Eodiscinid trilobite belonging to the family Weymouthiidae Kobayashi T. (1943), Order Agnostida It lived during the lower Middle Cambrian, with remains found in China (Xinjiang) and Australia (Queensland).
Serrodiscus Richter and Richter 1941. is a genus of Eodiscinid trilobite belonging to the family Weymouthiidae Kobayashi T. (1943), Order Agnostida. It lived during the late Lower Cambrian, with remains found in Canada, China (Gansu), The United Kingdom (England), Germany (Silesia), Poland, the Russian Federation, and the United States. It is named for the spines on the ventral side of the pygidium, which give it a serrated impression.
Bailiaspis Resser, 1936, is a Middle Cambrian (Miaolingian) trilobite genus belonging to the Family Conocoryphidae Angelin, 1854. Within the Acado-Baltic region, the genus ranges from Wuliuan into Guzhangian age strata.
Calodiscus is a genus of Eodiscinid trilobite in the family Calodiscidae. It lived during the late Lower Cambrian, with remains found in Canada, the United States, Greenland, The United Kingdom (England), Sweden, France, Germany, Italy (Sardinia), Kazakhstan, the Russian Federation and China.
