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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–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] |
Facial Suture
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. The stud ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 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. The stu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 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. The stu ... [...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 Specialization or Specialized may refer to: Academia * Academic specialization, may be a course of study or major at an academic institution or may refer to the field in which a specialist practices * Specialty (medicine), a branch of medical ... is common in the Ptychopariina, which has made it difficult for authors to develop a single type that can distinguish Ptychopariina from other clades. The thorax tends to be relatively long, with the pygidium generally smaller in size than the thorax. References External links''Ptychopariid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Olenina
''Olenina'' is an extinct suborder of the trilobite order Ptychopariida. Subdivisions *Superfamily Olenoidea **Family Ellipsocephaloididae **Family Olenidae Olenidae is a family of ptychopariid trilobites. Some genera, '' Balnibarbi'' and '' Cloacaspis'', are thought to have evolved a symbiotic relationship with sulfur-eating bacteria from which they derived nutrition. Genera * Acerocare * Acero ... *Superfamily ''Incertae sedis'' **Genus '' Triarthrus'' References Ptychopariida Arthropod suborders {{ptychopariida-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Proetida
Proetida is an order of trilobite that lived from the Ordovician to the Permian. It was the last order of trilobite to go extinct, finally 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. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Harpetida
Harpetida is one of the eleven orders of the extinct arthropod class Trilobita. The first harpetid trilobites appear in the Upper Cambrian, and the last species die out at the end of the Devonian period. Harpetid trilobites are characterized among trilobites by bearing a comparatively large, semicircular brim around the cephalon (head) which is often perforated by small pores. This brim is thought to serve as a filter-feeding apparatus. The brim stretches backward on either side of the cephalon (head) and typically has a pronounced suture along the outside. The compound eyes are typically reduced to small tubercles, though they have strong ridges stretching to the glabella (central region of the cephalon). They also typically have 12 or more thoracic segments. The pygidia are usually small. The families of Harpetida were formerly included in the order Ptychopariida, but were recently given their own order (Ebach & McNamara 2002). The subclass Librostoma was erected in 199 ... [...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. Thorax is usua ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Triarthrus
''Triarthrus'' is a genus of Upper Ordovician ptychopariid trilobite found in New York, Ohio, Kentucky, and Indiana, eastern and northern Canada, China and Scandinavia. It is the last of the Olenid trilobites, a group which flourished in the Cambrian period. The specimens of ''T. eatoni'' that are found in the Beecher's Trilobite Bed, Rome, New York area are exquisitely preserved showing soft body parts in iron pyrite. Pyrite preservation has given scientists a rare opportunity to examine the gills, walking legs, antennae, digestive systems, and eggs of trilobites, which are rarely preserved. ''Triarthrus'' is therefore commonly used in science texts to illustrate trilobite anatomy and physiology. Distribution * ''T. beckii'' Upper Caradoc and Ashgill, Snake Hill Formation, Cohoes, New York State; and Kentucky. * ''T. billingsi'' Ashgill?, Quebec * ''T. canadensis'' is known from the Upper Ordovician of Canada (Katian, lower Member of the Whitby Formation, Craigleith vicinity, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Olenidae
Olenidae is a family of ptychopariid trilobites. Some genera, ''Balnibarbi'' and ''Cloacaspis'', are thought to have evolved a symbiotic relationship with sulfur-eating bacteria from which they derived nutrition. Genera * Acerocare * Acerocarina * Aciculolenus *Anaximander * Angelina = Keidelaspis), * Apoplanias * Asilluchus * Baikonuraspis *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), * Isidrella * Jujuyaspis (= Alimbetaspis), * Leiobienvillia * Leptoplastides (= Andesaspis;= Beltella; = Chunkingaspis; = Parabolinopsis; * Rampartaspis), * Leptoplastus * Leurostega * Magnomma * Mesoctenopyge * Moxomia * Neoolenus * Neoparabolin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Damesellidae
Damesellidae is a family of odontopleurid trilobites found in late Middle to Late Cambrian marine strata, primarily of China. Damesellids are closely related to the odontopleurids of Odontopleuridae, but are not nearly as spinose, nor possess spines as exaggerated as Odontopleuridae. Like Odontopleuridae odontopleurids, damesellids have broad, bar-shaped cranidia with ledge-like borders. Damesellidae may represent transitional forms between more primitive, possibly ancestral ptychopariids and more advanced odontopleurids. Genera Genera include *?'' Adelogonus'' *'' Bergeronites'' *'' Blackwelderia'' *'' Blackwelderioides'' *'' Chiawangella'' *'' Cyrtoprora'' *'' Damesella'' *'' Damesops'' *'' Dipentaspis'' *'' Dipyrgotes'' *'' Neodrepanura'' *'' Duamsannella'' *'' Fengduia'' *'' Guancenshania'' *?'' Hercantyx'' *''Histiomona ''Histiomona'' is an extinct genus of damesellid odontopleurid trilobite. It lived from 501 to 490 million years ago during the Dresbachian faunal s ... [...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 tw ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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