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Peronopsidae
The Peronopsidae (which may also be called peronopsids) comprise the earliest family of the Agnostina suborder. Species of this family occurred on all paleocontinents. The earliest representatives of this family first occur just before the start of the Middle Cambrian, and the last disappeared just after the start of the Upper Cambrian. Distribution Peronopsidae are cosmopolitan. Temporal distribution Temporal distribution: * '' Archaeagnostus'', Toyonian ( ''Nephrolenellus multinodus''-zone) and Amgaian ('' Ovatoryctocara''-zone). * '' Eoagnostus'', Toyonian (''Nephrolenellus multinodus''-zone) and Amgaian (''Ovatoryctocara''-zone). * '' Peronopsis (Proacadagnostus)'', Amgaian (''Ovatoryctocara''- and lower ''Kounamkites''-zones). * '' Diplorrhina'', Amgaian (''Ovatoryctocara''- and ''Kounamkites''-zones) * '' Peronopsis (Peronopsis)'', Amgaian (''Ovatoryctocara''-, ''Kounamkites''- and ''Triplagnostus gibbus''-zones). * '' Pentagnostus (Pentagnostus)'', Amgaian (''Ovator ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acadagnostus
''Acadagnostus'' is a genus of trilobite from the Middle Cambrian, with 7 species currently recognized. The type species ''A. acadicus'' has the widest distribution known from any peronopsid (with ''Peronopsis, Peronopsis integer'' and ''P. scutalis'') and has been found in North America, Greenland, England, Western Europe, Eastern Europe, Central Asia, the Altai Mountains, the Siberian shield, China, and Australia. Etymology * ''ancisa'' is Latin meaning 'cut round', referring to the shape of the rear pygidial margin. * ''australis'' is Latin for 'southern'. * ''certus'' is Latin meaning 'definite' or 'sure'. * ''syrma'' is Ancient Greek meaning 'robe with a train', indicating the wide pygidial border in the rear. Description Like all Agnostida, ''Acadagnostus'' is diminutive, with the headshield (or Cephalon (arthropod head)#Trilobites, cephalon) and tailshield (or pygidium) of approximately the same size (or Pygidium#Trilobites, isopygous) and outline. Like all Agnostina ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peronopsis
''Peronopsis'' (meaning "broach-like" or possibly "boot-like") is a genus of trilobite restricted to the Middle Cambrian. Its remains have been found in Asia, Australia, Europe, and North America. Etymology The subgenus ''Svenax'' is a contraction of Sven Axel, the given names of the paleontologist Tullberg. Taxonomy Position of ''Peronopsis palmadon'' ''Peronopsis palmadon'' is intermediate between Peronopsidae and Condylopygidae, but it is not clear whether ''P. palmadon'' is ancestral to the Condylopigidae, a condylopigid exhibiting regression towards ancestral characters, or an example of parallel evolution. Species previously assigned to ''Peronopsis'' * ''P. acadica'' = '' Acadagnostus acadicus'' * ''P. bifidus'' = '' Pseudoperonopsis bifidus'' * ''P. bonnerensis'' = '' Pentagnostus (Meragostus) bonnerensis'' * ''P. brunfloensis'' = '' Redeagnostus brunfloensis'' * ''P. bulkurensis'' = '' Pentagnostus (Meragostus) bulkurensis'' * ''P. columbensis'' = '' Pseudo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diplorrhina
''Diplorrhina'' Hawle and Corda (1847) is a genus of trilobite belonging to Order Agnostida. It lived during the early Middle Cambrian ( Amgan and Mayan stages) in what are now the Czech Republic and the North Siberian plateau. as in members of the family Peronopsidae it lacks a preglabellar furrow. Both cephalon and pygidium lack spines. It is difficult to distinguish ''Diplorrhina'' from many other peronopsids. Taxonomy The ancestor of ''Diplorrhina'' is most likely one of the Siberian species of the genus ''Archaeagnostus ''Archaeagnostus'' is an extinct genus from a well-known class of fossil marine arthropods, the trilobite Trilobites (; meaning "three lobes") are extinct marine arthropods that form the class Trilobita. Trilobites form one of the earliest ...''. ''D. recta'' is the most primitive species and it gave rise to ''D. cuneifera'', which was in turn ancestral to ''Diplorrhina triplicata''. Species previously assigned to ''Diplorrhina'' * ''D. normat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Itagnostus
''Itagnostus'' is a genus of trilobite restricted to the Middle Cambrian. Its remains have been found in Asia, Australia, Europe, and North America. Distribution * ''Itagnostus elkedrensis'' occurs in the Middle Cambrian of Australia (''Ptychagnostus praecurrens''-zone, ''Xystridura templetonensis''-zone, and ''Dinesus''-stage, Elkedra; ''Triplagnostus gibbus''-zone, Sandover Beds; both Northern Territory), the Russian Federation (''Kounamkites''-zone, Nekekit River; ''Liostracus allachjunensis''-zone, Lena River). * ''Itagnostus comis'' is found in the Middle Cambrian of Australia (''Triplagnostus gibbus''-zone, Sandover Beds, Northern Territory). * ''Itagnostus gaspensis gaspensis'' is reported from the Middle Cambrian of the United States (Geddes Formation, Nevada; ''Ptychagnostus atavus''-zone, Wheeler Formation, Drum Mountains, Utah), Canada (upper part, Grosses Roches, St. Laurence, Quebec), Russian Federation (''Tomagnostus fissus''-zone, Lena River). * ''Itagnostus gas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eodiscina
Eodiscina is trilobite suborder. The Eodiscina first developed near the end of the Lower Cambrian period (late Atdabanian) and became extinct at the end of the Middle Cambrian. Species are tiny to small, and have a thorax of two or three segments. Eodiscina includes six families classified under one superfamily, Eodiscoidea. Taxonomy The Eodiscina are mostly considered the more primitive suborder of the Agnostida, and the Agnostina the more advanced. Some scholars do not consider the Agnostina true trilobites, and consequently rejected the idea that they were related to the Eodiscina. Consequently, these scientists have proposed to elevate the group to ordinal level, which would thus be called Eodiscida Kobayashi, 1939. Origin The oldest known eodiscoid is ''Tsunyidiscus''. The glabella of ''Tsunyidiscus'' is extremely similar to that of ''Dipharus clarki'', and distinct from all other eodiscoids. ''D. clarki'' is thought to represent an immature stage of the redlichioid ''Bu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pentagnostus
''Pentagnostus'' is a genus of trilobites restricted to the Middle Cambrian. Its remains have been found in Siberia, Australia, North America, Scandinavia, and Kazakhstan. Taxonomy The probable ancestor of ''Pentagnostus'' is Archaeagnostus. Two subgenera can be distinguished. The nominate subgenus occurred first and developed into the later subgenus ''Pentagnostus (Meragnostus)'' and the family Ptychagnostidae Ptychagnostidae is a family of agnostid trilobites from the 5th Stage to the Paibian Age of the Cambrian ( to million years ago). The family includes several important index fossils. Description Like all agnostids, ptychagnostids have cep .... Species and distribution Subgenus ''Pentagnostus (Pentagnostus)'' * ''P. anabarensis'' Lermontova, 1940 ( type) * ''P. ademptus'' (Prokovskaya and Jegorova, 1972) * ''P. brighamensis'' (Resser, 1938) * ''P. shergouldi'' Laurie, 2004 * ''P. veles'' Öpik, 1979 synonym ''P. endemicus''. Subgenus ''Pentagnostus (Mera ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eoagnostus
''Eoagnostus'' is an extinct genus from a well-known class of fossil marine arthropods, the trilobites. It lived during the terminal Lower Cambrian (Toyonian), until the earliest Middle Cambrian (earliest ''Kounamkites''-zone, part of the lower Amgaian). Distribution * ''E. roddyi'' terminal Lower Cambrian of the United States (''Bonnia''-zone, Kinzers Shale, Lancaster, New York; Pennsylvania; Vermont)Whittington, H. B. et al. Part O, Treatise on Invertebrate Paleontology. Revised, Volume 1 – Trilobita – Introduction, Order Agnostida, Order Redlichiida. 1997 and the early Middle Cambrian of Newfoundland, and Greenland (around the boundary of ''Ovatoryctocara''-zone, Henson Gletscher Formation). * ''E. acrorhachis'' occurs in the terminal Lower Cambrian of the United States (''Bonnia''-zone, Hatch Hill, New York). Description Almost identical to Archaeagnostus, but the frontal lobe of the central raised area of the cephalon (or glabella The glabella, in humans, is the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Archaeagnostus
''Archaeagnostus'' is an extinct genus from a well-known class of fossil marine arthropods, the trilobite Trilobites (; meaning "three lobes") 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 ...s. It lived from the terminal Toyonian to early Amgaian. Species belonging to this genus have been found in Eastern North America, Newfoundland, the Henson Gletscher Formation in Greenland, the Nekekit and Molodo Rivers in Eastern Siberia, and in Guizhou, China. References Cambrian trilobites of North America Peronopsidae Agnostida genera Extinct animals of North America Cambrian trilobites of Asia Paleozoic life of Quebec {{agnostida-stub Cambrian genus extinctions ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quadragnostus
''Quadragnostus'' is an extinct genus from a well-known class of fossil marine arthropods, the trilobites. It lived during the Cambrian Period The Cambrian Period ( ; sometimes symbolized C with bar, Ꞓ) was the first geological period of the Paleozoic Era, and of the Phanerozoic Eon. The Cambrian lasted 53.4 million years from the end of the preceding Ediacaran Period 538.8 million ..., which lasted from approximately 539 to 485 million years ago. References Cambrian trilobites Peronopsidae Agnostida genera {{agnostida-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tannudiscus
''Tannudiscus'' Pokrovskaya (1959) is a genus of Eodiscinid trilobites belonging to the family Weymouthiidae Kobayashi T. (1943), Order Agnostida (Salter 1864). It lived during the late Lower Cambrian, with remains found in Canada (Newfoundland), China (Gansu), The United Kingdom (England), and the Russian Federation (Tuva, Gorno-Altayskaya). TYPE SPECIES: ''T. tannulaicus'' Pokrovskaya, 1959. Taxonomy The Weymouthiid family shows a trend of shortening the occipital ring. In '' Chelediscus'' and ''Tannudiscus'' the occipital ring is entirely obliterated as in the Agnostina suborder. ''Tannudiscus'' has some other characters it shares with the Agnostina, such as a glabella consisting of two lobes and the occipital ring divided into basal glabellar lobes. Both the glabella and pygidial axis are isolated from the border furrow, and the latter is undivided. It is therefore considered likely that the Agnostina descended directly from a species assignable to ''Tannudiscus''. The ea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Agnostida
Agnostida is an order of arthropod which have classically been seen as a group of highly modified trilobites, though some recent research has doubted this placement. Regardless, they appear to be close relatives as part of the Artiopoda. They are present in the Lower Cambrian fossil record along with trilobites from the Redlichiida, Corynexochida, and Ptychopariida orders, and were highly diverse throughout the Cambrian. Agnostidan diversity severely declined during the Cambrian-Ordovician transition, and the last agnostidans went extinct in the Late Ordovician. Systematics The Agnostida are divided into two suborders — Agnostina and Eodiscina — which are then subdivided into a number of families. As a group, agnostids are isopygous, meaning their pygidium is similar in size and shape to their cephalon. Most agnostid species were eyeless. The systematic position of the order Agnostida within the class Trilobita remains uncertain, and there has been continuing deb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus comes above species and below family (taxonomy), family. In binomial nomenclature, the genus name forms the first part of the binomial species name for each species within the genus. :E.g. ''Panthera leo'' (lion) and ''Panthera onca'' (jaguar) are two species within the genus ''Panthera''. ''Panthera'' is a genus within the family Felidae. The composition of a genus is determined by taxonomy (biology), taxonomists. The standards for genus classification are not strictly codified, so different authorities often produce different classifications for genera. There are some general practices used, however, including the idea that a newly defined genus should fulfill these three criteria to be descriptively useful: # monophyly – all descendants ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
