Ptychopariida Genera

	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 (arthropod anatomy), cephalon meets the Trilobite#Terminology, 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 ecdysis, 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 i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu]
	Elrathia Kingii ''Elrathia'' is a genus of trilobite belonging to Ptychopariacea known from the mid-Cambrian of Laurentia (North America). ''E. kingii'' is one of the most common trilobite fossils in the USA locally found in extremely high concentrations within the Wheeler Formation in the U.S. state of Utah. ''E. kingii'' has been considered the most recognizable trilobite. Commercial quarries extract ''E. kingii'' in prolific numbers, with just one commercial collector estimating 1.5 million specimens extracted in a 20-year career. 1950 specimens of ''Elrathia'' are known from the Greater Phyllopod bed, where they comprise 3.7% of the community. Etymology Even though the generic name ''Elrathia'' was first published in the combination ''E. kingii'', a species from the House Range, Utah, the name, itself, is derived from Elrath, Cherokee County, Alabama. Description ''E. kingii'' is a medium-sized trilobite with a smooth sub-ovate carapace that is tapered towards the rear. Trilobite#Ter ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu]
	Phacopida Phacopida ("lens-face") is an order of trilobites that lived from the Late Cambrian to the Late Devonian. It is made up of a morphologically diverse assemblage of taxa in three related suborders. Characteristics Phacopida had 8 to 19 thoracic segments and are distinguishable by the expanded glabella, short or absent preglabellar area, and schizochroal (Phacopina) or holochroal (Cheirurina and Calymenina) eyes. Schizochroal eyes are compound eyes with up to around 700 separate lenses. Each lens has an individual cornea which extended into a rather large sclera. The development of schizochroal eyes in phacopid trilobites is an example of post-displacement paedomorphosis. The eyes of immature holochroal Cambrian trilobites were basically miniature schizochroal eyes. In Phacopida, these were retained, via delayed growth of these immature structures (post-displacement), into the adult form. '' Eldredgeops rana'' (Phacopidae) and '' Dalmanites limulurus'' (Dalmanitidae) are two ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu]
	Ellipsocephaloidea Ellipsocephaloidea is a superfamily of trilobites that lived during the Cambrian period. It was first described by Lin in 1990. Taxonomy According to the Fossilworks database, Ellipsocephaloidea belongs to the order Redlichiida and includes several families, such as Agraulidae, Bigotinidae, Ellipsocephalidae, Estaingiidae, Palaeolenidae, and Yunnanocephalidae, although it is now thought the superfamily is within the Ptychopariida 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–Siluria ... Agraulidae Agraulidae is a family of trilobites within the superfamily Ellipsocephaloidea. Members of this family are characterized by their large size and distinctive cephalic features. Bigotinidae Bigotinidae is another family of trilobites within the superfamily Ellipsocephaloidea. Members of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu]
	Ptychopariina Ptychopariina is an extinct suborder of trilobites of the order Ptychopariida.Swinnerton HH, 1915. Suggestions for a Revised Classification of trilobites. ''Geological Magazine''. Also known as the ''primitive Ptychopariida'', they are a notably wide and varied taxon. Some of the representative genera include '' Elrathia'', '' Densonella'', '' Norwoodia'', '' Tricrepicephalus'', '' Conocoryphe'', and '' Modocia''. Description Specialization is common in the Ptychopariina, which has made it difficult for authors to develop a single type that can distinguish Ptychopariina from other clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...s. The thorax tends to be relatively long, with the pygidium generally smaller in size than the thorax. References External links''Ptychopariida ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu]
	Olenidae Olenidae is a family of ptychopariida, ptychopariid trilobites. Some genera, ''Balnibarbi (trilobite), Balnibarbi'' and ''Cloacaspis'', are thought to have evolved a symbiosis, symbiotic relationship with sulfur-eating bacteria from which they derived nutrition. Genera ''Acerocare'' ''Acerocarina'' ''Aciculolenus'' ''Anaximander (trilobite), Anaximander'' ''Angelina (trilobite), Angelina'' (=''Keidelaspis''), ''Apoplanias'' ''Asilluchus'' ''Baikonuraspis'' ''Balnibarbi (trilobite), Balnibarbi'' ''Bienvillia'' (=''Diatemnus''; =''Mendoparabolina'') ''Boeckaspis'' (/''Boeckia'' BROGGER; =''Sphaerophthalmella'') ''Bondarevites'' ''Bulbolenus'' ''Chekiangaspis'' ''Cloacaspis'' ''Ctenopyge'' ''Cyclognathina'' ''Danarcus'' ''Desmetia'' ''Eoctenopyge'' ''Euonchonotina'' ''Eurycare'' ''Granitzia'' ''Hancrania'' ''Helieranella'' ''Highgatella'' ''Huangshiaspis'' ''Hunanolenus'' ''Hypermecaspis'' (=''Spitsbergaspis''), ''Inkouia'' (=''Agalatus''), ''Isidrel ... [...More Info...] [...Related Items...] OR:* [Wikipedia] [Google] [Baidu]