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Bourgueticrinida
Bourgueticrinida is an order of crinoids that typically live deep in the ocean. Members of this order are attached to the seabed by a slender stalk and are known as sea lilies. While other groups of crinoids flourished during the Permian, bourgueticrinids along with other extant orders did not appear until the Triassic, following a mass extinction event in which nearly all crinoids died out. Taxonomy Bourgueticrinida has traditionally been viewed as an order of Articulata and a sister taxon to the order Comatulida, the feather stars. A study published in 2011 suggested that it should be renamed Bourgueticrinina and viewed as a suborder of Comatulida. Characteristics Sea lilies are crinoids with a calyx and five pairs of feather-like arms standing on a long stalk which is retained throughout the animal's life. This stalk is attached to the substrate by means of an enlarged, terminal disc or alternatively by means of several branching, irregular radicular cirri arising from the l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bourgueticrinidae
Bourgueticrinidae is a family of crinoids, containing 2 genera Genus (; : genera ) is a taxonomic rank above species and below family as used in the biological classification of living and fossil organisms as well as viruses. In binomial nomenclature, the genus name forms the first part of the binomial s .... Genera * '' Conocrinus'' d'Orbigny, 1850 * '' Democrinus'' Perrier, 1883 References * Thuy B, Gale AS, Kroh A, Kucera M, Numberger-Thuy LD, Reich M, et al. (2012) Ancient Origin of the Modern Deep-Sea Fauna. PLoS ONE 7(10): e46913. doi:10.1371/journal.pone.0046913 Bourgueticrinida Echinoderm families Extant Early Cretaceous first appearances {{crinoidea-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Comatulida
Comatulida is an order of crinoids Crinoids are marine invertebrates that make up the class Crinoidea. Crinoids that remain attached to the sea floor by a stalk in their adult form are commonly called sea lilies, while the unstalked forms, called feather stars or comatulids, are .... Members of this order are known as feather stars and mostly do not have a stalk as adults. The oral surface with the mouth is facing upwards and is surrounded by five, often divided rays with feathery pinnules. Comatulids live on the seabed and on reefs in tropical and temperate waters. Taxonomy Bourgueticrinida, the sea lilies, has traditionally been viewed as an order of Articulata and a sister taxon to Comatulida. A study published in 2011 suggested that it should be renamed Bourgueticrinina and viewed as a suborder of Comatulida. Characteristics Like other echinoderms, comatulids have pentamerous symmetry (five sided) as adults though the larvae have bilateral symmetry. Late in their deve ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Articulata (Crinoidea)
Articulata are a subclass or superorder within the class Crinoidea, including all living crinoid species. They are commonly known as sea lilies (stalked crinoids) or feather stars (unstalked crinoids). The Articulata are differentiated from the extinct subclasses by their lack of an anal plate in the adult stage and the presence of an entoneural system. Articulata first appeared in the fossil record during the Triassic period although other, now extinct crinoid groups, originated in the Ordovician. Characteristics Articulata exhibit pentamerous symmetry. The stalk, which consists of numerous disks held together by ligaments, supports a calyx or cup made of circlets of calcerous plates. In Comatulids, the stalk develops following the larval stage, but the juveniles shed all but the topmost disk to take up a free-living existence. Five often branched arms, which consist of articulated series of ossicles, extend from the oral plate and form the food-capture mechanism of Articulata. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bathycrinidae
Bathycrinidae is a family of echinoderms in the class Crinoidea. It contains the following genera and species: * '' Bathycrinus'' Wyville Thomson, 1872 ** '' Bathycrinus aldrichianus'' Wyville Thomson, 1877 ** ''Bathycrinus australis ''Bathycrinus'' is a genus of crinoid Crinoids are marine invertebrates that make up the class Crinoidea. Crinoids that remain attached to the sea floor by a stalk in their adult form are commonly called sea lilies, while the unstalked forms ...'' AH Clark, 1907 ** '' Bathycrinus australocrucis'' McKnight, 1973 ** '' Bathycrinus carpenterii'' (Danielssen & Koren, 1877) ** '' Bathycrinus gracilis'' Wyville Thomson, 1877 ** '' Bathycrinus mendeleevi'' Mironov, 2008 * '' Discolocrinus'' Mironov, 2008 ** '' Discolocrinus thieli'' Mironov, 2008 * '' Monachocrinus'' AH Clark, 1919 ** '' Monachocrinus aotearoa'' McKnight, 1973 ** '' Monachocrinus caribbeus'' (AH Clark, 1908) ** '' Monachocrinus mortenseni'' Gislén, 1938 ** '' Monachocrinus paradoxus ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sessility (zoology)
Sessility is the biological property of an animal describing its lack of a means of self-locomotion. Sessile animals for which natural ''motility'' is absent are normally immobile. This is distinct from the botanical concept of sessility, which refers to an organism or biological structure attached directly by its base without a stalk. Sessile animals can move via external forces (such as water currents), but are usually permanently attached to something. Organisms such as corals lay down their own substrate from which they grow. Other organisms grow from a solid object, such as a rock, a dead tree trunk, or a human-made object such as a buoy or ship's hull. Mobility Sessile animals typically have a motile phase in their development. Sponges have a motile larval stage and become sessile at maturity. Conversely, many jellyfish develop as sessile polyps early in their life cycle. In the case of the cochineal, it is in the nymph stage (also called the crawler stage) that the c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Echinoderm Orders
An echinoderm () is any animal of the phylum Echinodermata (), which includes starfish, brittle stars, sea urchins, sand dollars and sea cucumbers, as well as the sessile sea lilies or "stone lilies". While bilaterally symmetrical as larvae, as adults echinoderms are recognisable by their usually five-pointed radial symmetry (pentamerous symmetry), and are found on the sea bed at every ocean depth from the intertidal zone to the abyssal zone. The phylum contains about 7,600 living species, making it the second-largest group of deuterostomes after the chordates, as well as the largest marine-only phylum. The first definitive echinoderms appeared near the start of the Cambrian. Echinoderms are important both ecologically and geologically. Ecologically, there are few other groupings so abundant in the deep sea, as well as shallower oceans. Most echinoderms are able to reproduce asexually and regenerate tissue, organs and limbs; in some cases, they can undergo complete regener ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genus
Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In binomial nomenclature, the genus name forms the first part of the binomial species name for each species within the genus. :E.g. ''Panthera leo'' (lion) and ''Panthera onca'' (jaguar) are two species within the genus ''Panthera''. ''Panthera'' is a genus within the family Felidae. The composition of a genus is determined by taxonomy (biology), taxonomists. The standards for genus classification are not strictly codified, so different authorities often produce different classifications for genera. There are some general practices used, however, including the idea that a newly defined genus should fulfill these three criteria to be descriptively useful: # monophyly – all descendants of an ancestral taxon are grouped together (i.e. Phylogeneti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fossiliferous Limestone
Fossiliferous limestone is a type of limestone that contains noticeable quantities of fossils or trace fossil, fossil traces. If a particular type of fossil dominates, a more specialized term can be used as in "Ames Limestone, Crinoidal", "Coralline", "Conchoidal" limestone. If seashells, shell fragments, and shell sand form a significant part of the rock, a term "shell limestone" is used. The fossils in these rocks may be of macroscopic or microscopic size. The sort of macroscopic fossils often include crinoid stems, brachiopods, gastropods, and other hard shelled mollusk remains. In some cases, microfossils such as siliceous diatom shells in deposition may convert over time to opal and chert, providing the only inferred evidence of bioactivity preserved in limestone. Fossiliferous limestone is termed biosparite under the Folk classification of sedimentary rocks. Lagerstätte are a class of fossil bearing rocks that includes fossiliferous limestone. Use Fossils in general pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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] |
Burgess Shale
The Burgess Shale is a fossil-bearing deposit exposed in the Canadian Rockies of British Columbia, Canada. It is famous for the exceptional preservation of the soft parts of its fossils. At old (middle Cambrian), it is one of the earliest fossil beds containing soft-part imprints. The rock unit is a black shale and crops out at a number of localities near the town of Field in Yoho National Park and the Kicking Horse Pass. Another outcrop is in Kootenay National Park 42 km to the south. History and significance The Burgess Shale was discovered by palaeontologist Charles Walcott on 30 August 1909, towards the end of the season's fieldwork. He returned in 1910 with his sons, daughter, and wife, establishing a quarry on the flanks of Fossil Ridge. The significance of soft-bodied preservation, and the range of organisms he recognised as new to science, led him to return to the quarry almost every year until 1924. At that point, aged 74, he had amassed over 65,000 s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
