Paleonelsonia

	Paleonelsonia ''Paleonelsonia'' is a fossil genus of trilobites belonging to the family Ptychopariidae Ptychopariidae is a family of trilobites, containing the following genera: '' Achlysopsis'' '' Altikolia'' '' Altitudella'' '' Amecephalites'' '' Asthenopsis'' '' Austinvillia'' '' Balangcunaspis'' ''Bashania'' '' Bathyholcus'' '' Bathy .... References Ptychopariida genera Ptychopariidae {{trilobite-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu]
	Ptychopariidae Ptychopariidae is a family of trilobites, containing the following genera: '' Achlysopsis'' '' Altikolia'' ''Altitudella'' '' Amecephalites'' ''Asthenopsis'' '' Austinvillia'' '' Balangcunaspis'' '' Bashania'' '' Bathyholcus'' '' Bathyocos'' '' Billingsaspis'' '' Binodaspis'' ''Blairella'' – see '' Neoblairella'' '' Bolaspidina'' '' Brunswickia'' '' Bulkuraspis'' '' Caborcella'' '' Callidaspina'' '' Callidaspis'' '' Cathayanella'' ''Champlainia'' '' Chengshanaspis'' '' Chinghisicus'' '' Chunghwaella'' '' Conopolus'' '' Dananzhuangia'' '' Deltina'' '' Douposiella'' '' Elrathina'' '' Entsyna'' '' Eodouposiella'' '' Eokochaspis'' '' Eosoptychoparia'' '' Eospencia'' '' Eurostina'' '' Finecrestia'' '' Gaotanaspis'' '' Gaphuraspis'' '' Gedongaspis'' ''Gunnia'' '' Hadrocephalites'' '' Hadrokraspedon'' '' Hamptonella'' '' Hejinaspis'' '' Hemicricometopus'' '' Hewenia'' '' Holasaphus'' '' Horbusonia'' '' Illtydaspis'' '' Jangudaspis' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu]
picture info	Trilobites 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 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. By the time trilobites first appeared in the fossil record, they were already highly diversified and geographically dispersed. Because trilobites had wide diversity and an easily fossilized exoskeleton, they left an extensive fossil record. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu]
	Ptychopariida Genera Ptychopariida is a large, heterogeneous order of trilobite containing some of the most primitive species known. The earliest species occurred in the second half of the Lower Cambrian, and the last species did not survive the Ordovician–Silurian extinction event. Trilobites have facial sutures that run along the margin of the glabella and/or fixigena to the shoulder point where the cephalon meets the thorax. These sutures outline the cranidium, or the main, central part of the head that does not include the librigena (free cheeks). The eyes are medial along the glabella on the suture line (and some species have no eyes). The fossils of the moults of trilobites can often be told from the fossils of the actual animals by whether the librigena are present. (The librigena, or cheek spines, detach during moulting.) In ptychopariids, short bladelike genal spines are often present on the tips of the librigena. The thorax is large and is typically made up of eight or more segments. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu]