Proetida Genera

	Proetida Genera Proetida is an order of trilobite that lived from the Ordovician to the Permian. It was the last surviving order of trilobite, dying out in the Permian-Triassic extinction event. Description These typically small trilobites resemble those of the order Ptychopariida, from which the new order Proetida was separated in 1975 by Fortey and Owens. Like the order Phacopida, the proetids have exoskeletons that sometime have pits or small tubercles, especially on the glabella (middle portion of the head). Because of their resemblance to the Ptychopariida in some features, the proetids are included in the subclass Librostoma. Unlike the trilobites of the phacopid suborder Phacopina, whose eyes are schizochroal, the proetids have the more common holochroal eyes. These eyes are characterized by close packing of biconvex lenses beneath a single corneal layer that covers all of the lenses. Each lens is generally hexagonal in outline and in direct contact with the others. They range ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu]
picture info	Ordovician The Ordovician ( ) is a geologic period and System (geology), system, the second of six periods of the Paleozoic Era (geology), Era, and the second of twelve periods of the Phanerozoic Eon (geology), Eon. The Ordovician spans 41.6 million years from the end of the Cambrian Period Megaannum, Ma (million years ago) to the start of the Silurian Period Ma. The Ordovician, named after the Celtic Britons, Welsh tribe of the Ordovices, was defined by Charles Lapworth in 1879 to resolve a dispute between followers of Adam Sedgwick and Roderick Murchison, who were placing the same Rock (geology), rock beds in North Wales in the Cambrian and Silurian systems, respectively. Lapworth recognized that the fossil fauna in the disputed Stratum, strata were different from those of either the Cambrian or the Silurian systems, and placed them in a system of their own. The Ordovician received international approval in 1960 (forty years after Lapworth's death), when it was adopted as an official per ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu]
	Proetidae Proetidae is a family (biology), family of Proetida, proetid trilobites. The first species appeared in the Upper Ordovician, and the last genera survived until the Middle Permian. However, if the closely related family Phillipsiidae is actually a subfamily of Proetidae, then the proetids of Proetidae survive until the end of the Permian, where the last perish during the Permian–Triassic extinction event. Genera Proetidae ostensibly contains these following genera, though many may be placed in Phillipsiidae if the latter is, indeed, a distinct family. ''Aayemenaytcheia'' ''Aceroproetus'' ''Alaskalethe'' ''Altajaspis'' ''Anambon'' ''Anglibole'' ''Angustibole'' ''Anujaspis'' ''Appendicysta'' ''Aprathia'' ''Archaeocoryphe'' ''Ascetopeltis'' ''Astroproetus'' (syn=''Xiushuiproetus'', ''Zhejiangoproetus'') ''Australokaskia'' ''Bailielloides'' ''Bapingaspis'' ''Basidechenella'' ''Beleckella'' ''Belgibole'' ''Benesovella'' ''Bitumulina'' ''Blodgettia'' ''Bohemipro ... [...More Info...] [...Related Items...] OR:* [Wikipedia] [Google] [Baidu]
	Alokistocaridae Alokistocaridae is a family of ptychopariid trilobites that lived from the Botomian epoch of the Early Cambrian until the Late Cambrian. Alokistocarids were particle feeders and left small furrows which are occasionally preserved.Coppold, Murray and Wayne Powell (2006). ''A Geoscience Guide to the Burgess Shale'', p.54. The Burgess Shale Geoscience Foundation, Field, British Columbia. . Their remains are found worldwide. '' Elrathia kingii'', one of the most collected trilobites in the world, is a typical alokistocarid. Description Alokistocarids have an exoskeleton that is elongated ovate to inverted egg-shaped. The headshield (or cephalon) is semicircular and has a well-defined border. The central raised area of the cephalon (or glabella) is somewhat tapering forward, generally with 3 or 4 pairs of more or less distinct lateral furrows. The front of the glabella is rounded or truncate, and is separated from the border by a wide, moderately convex to flat (or rarely concave) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu]
	Telephinidae Telephinidae is a family of pelagic trilobites with large wide-angle eyes, occupying most of the free cheeks, downward directed facial spines and 9-10 thorax segments. The family is known during the entire Ordovician and occurred in deep water around the globe. Distribution The Telephinidae probably evolved from a species assigned to the Hystricuridae. Telephinids first occur during the late Tremadocian, with ''Carolinites'' and ''Opipeuterella'' being globally very common at low latitudes by the end of the Floian. ''Carolinites'' survived into the Darriwilian, at which time a second major radiation occurred, that includes ''Telephina'' and ''Telephops'', and these genera only became extinct at the end of the Ordovician. Description The central raised area of the headshield (or glabella) is strongly convex. The most backward segment (called occipital ring) is wide and is defined by a deep furrow. No further segments can be determined in front of the occipital ring, but someti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu]