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Pentacrinoidea
Pentacrinoidea is a subclass of crinoids containing all members of Crinoidea except for the exclusively Paleozoic camerates (subclass Camerata). It was originally named in 1918 by Otto Jaekel, who hypothesized a fundamental split between camerate and non-camerate crinoids. Later workers doubted this interpretation, and Pentacrinoidea was rarely used during the rest of the 20th century. Recent phylogenetic work has provided strong support for Jaekel's hypothesis, and Pentacrinoidea was reinstated in a 2017 revision of crinoid systematics. Pentacrinoidea includes most major crinoid groups, such as the living Articulata and extinct Flexibilia (together forming the parvclass Cladida) as well as the extinct Disparida. It is a stem-based taxon, defined as including all crinoids closer to ''Pentacrinites'' (a Jurassic articulate) or '' Apektocrinus'' (an Early Ordovician The Ordovician ( ) is a geologic period and system, the second of six periods of the Paleozoic Era. The Ordo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crinoidea
Crinoids are marine animals that make up the class Crinoidea. Crinoids that are attached to the sea bottom by a stalk in their adult form are commonly called sea lilies, while the unstalked forms are called feather stars or comatulids, which are members of the largest crinoid order, Comatulida. Crinoids are echinoderms in the phylum Echinodermata, which also includes the starfish, brittle stars, sea urchins and sea cucumbers. They live in both shallow water and in depths as great as . Adult crinoids are characterised by having the mouth located on the upper surface. This is surrounded by feeding arms, and is linked to a U-shaped gut, with the anus being located on the oral disc near the mouth. Although the basic echinoderm pattern of fivefold symmetry can be recognised, in most crinoids the five arms are subdivided into ten or more. These have feathery pinnules and are spread wide to gather planktonic particles from the water. At some stage in their lives, most crinoids have ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crinoid
Crinoids are marine animals that make up the class Crinoidea. Crinoids that are attached to the sea bottom by a stalk in their adult form are commonly called sea lilies, while the unstalked forms are called feather stars or comatulids, which are members of the largest crinoid order, Comatulida. Crinoids are echinoderms in the phylum Echinodermata, which also includes the starfish, brittle stars, sea urchins and sea cucumbers. They live in both shallow water and in depths as great as . Adult crinoids are characterised by having the mouth located on the upper surface. This is surrounded by feeding arms, and is linked to a U-shaped gut, with the anus being located on the oral disc near the mouth. Although the basic echinoderm pattern of fivefold symmetry can be recognised, in most crinoids the five arms are subdivided into ten or more. These have feathery pinnules and are spread wide to gather planktonic particles from the water. At some stage in their lives, most crinoids have ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cladida
Cladida is a major subgroup of crinoids with a complicated taxonomic history. Cladida was originally applied to a wide assortment of extinct crinoids with a dicyclcic calyx. Under this original definition, cladids would represent a paraphyletic order ancestral to several other major crinoid groups, particularly the living Articulata. More recently, Cladida has been redefined as a monophyletic parvclass of pentacrinoids which encompasses articulates and the extinct Flexibilia (flexibles). Cladids also include various minor taxa such as the hybocrinids and " cyathocrines". As flexibles were not originally considered cladids, the new subgroup Eucladida has been erected for cladids which are more derived than flexibles. Cladida is the sister group to Disparida, another large group of extinct crinoids. Taxonomy * Parvclass Cladida ** Superorder † Porocrinoidea *** Order † Hybocrinida *** Order † Porocrinida ** Superorder † Flexibilia *** Order † Sagenocrinida *** O ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Camerata (Crinoidea)
The Camerata or camerate crinoids are an extinct subclass of Paleozoic stalked crinoids. They were some of the earliest crinoids to originate during the Early Ordovician, reached their maximum diversity during the Mississippian, and became extinct during the Permian–Triassic extinction event. Camerates are the sister group of Pentacrinoidea, which contains all other crinoids (including living species). The two largest camerate subgroups are the orders Diplobathrida and Monobathrida. Anatomically, they are distinguished by:Treatise on Invertebrate Paleontology, Volume T. Echinodermata: Crinoidea. Ubaghs et al. Editors: R. C. Moore and C. Teichert. 1978. *fused junctions between the plates of the cup *brachial plates incorporated into the cup *tegmen forming a rigid roof over the mouth *no less than ten and sometimes a very large number of free arms, often pinnulate Subdivisions * Order Cladida? * '' Adelphicrinus'' * '' Eknomocrinus'' * '' Cnemecrinus'' * '' Quechuacrinus' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jurassic
The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The Jurassic constitutes the middle period of the Mesozoic, Mesozoic Era and is named after the Jura Mountains, where limestone strata from the period were first identified. The start of the Jurassic was marked by the major Triassic–Jurassic extinction event, associated with the eruption of the Central Atlantic magmatic province, Central Atlantic Magmatic Province. The beginning of the Toarcian Stage started around 183 million years ago and is marked by an extinction event associated with widespread Anoxic event, oceanic anoxia, ocean acidification, and elevated temperatures likely caused by the eruption of the Karoo-Ferrar, Karoo-Ferrar large igneous provinces. The end of the Jurassic, however, has no clear boundary with the Cretaceous and i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Node-based Taxon
Phylogenetic nomenclature is a method of nomenclature for taxa in biology that uses phylogenetic definitions for taxon names as explained below. This contrasts with the traditional approach, in which taxon names are defined by a '' type'', which can be a specimen or a taxon of lower rank, and a description in words. Phylogenetic nomenclature is currently regulated by the '' International Code of Phylogenetic Nomenclature'' (''PhyloCode''). Definitions Phylogenetic nomenclature ties names to clades, groups consisting of an ancestor and all its descendants. These groups can equivalently be called monophyletic. There are slightly different ways of specifying the ancestor, which are discussed below. Once the ancestor is specified, the meaning of the name is fixed: the ancestor and all organisms which are its descendants are included in the named taxon. Listing all these organisms (i.e. providing a full circumscription) requires the full phylogenetic tree to be known. In practice, ther ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Actinocrinites
''Actinocrinites'' (from el, ἀκτίς , 'ray' and el, κρίνω 'to perceive') is an extinct genus of crinoids. Fossil records This genus is known in the fossil record from the Devonian period to the Permian period (age range: 360.7 to 290.1 million years ago). Fossils of species within this genus have been found in Australia, China, Europe and United States. Species Species within this genus include: *†''Actinocrinites batheri'' Whidborne 1896 *†''Actinocrinites brouweri'' Wanner 1924 *†''Actinocrinites zhaoae'' Waters et al. 2003 *†''Actinocrinites triacontadactylus'' References Monobathrida Devonian crinoids Carboniferous animals of Europe Prehistoric echinoderms of Europe Mississippian animals of North America Devonian first appearances Permian genus extinctions Carboniferous crinoids Permian crinoids {{paleo-crinoidea-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Early Ordovician
The Ordovician ( ) is a geologic period and system, the second of six periods of the Paleozoic Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period million years ago (Mya) to the start of the Silurian Period Mya. The Ordovician, named after the 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 beds in North Wales in the Cambrian and Silurian systems, respectively. Lapworth recognized that the fossil fauna in the disputed 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 period of the Paleozoic Era by the International Geological Congress. Life continued to flourish during the Ordovician as it did in the earlier Cambr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
