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Saint-Chinian Formation
The Saint-Chinian Formation is a geological formation composed of shales with limestone inclusions, dating from the Lower Ordovician (Tremadocian). It is one of the six geological formations from the Saint-Chinian Cambro-Ordovician basin, comprising, from the most ancient to the most recent : La Dentelle Formation, Saint-Chinian Formation, La Maurerie Formation, Cluse de l'Orb Formation and Setso member, Foulon Formation and Landeyran Formation. This formation outcrops on the southern flanks of the Montagne Noire in Southern France.. The formation received its name from the small city of Saint-Chinian, a commune located in the Hérault department in Occitania. It is dated from the biostratigraphic sub-zone characterized by Taihungshania miqueli and Asaphelina barroisi berardi. Paleoenvironment The thin nature of the silico-clastics deposits, the presence of slump, combined with a trilobite fauna dominated by members of the Asaphidae family indicates a marine environment of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geragnostus
''Geragnostus'' is a genus of very small agnostid trilobites whose fossils are found Ordovician-aged marine strata from Eurasia, North America and Argentina. Etymology * ''balanolobus'' is derived from the Greek 'balanos', acorn, and 'lobos', lobe, in reference to the outline of the rear lobe of the rhachis. * ''sidenbladhi'' has been named in honor of the Swedish philosopher and paleontologist Elis Sidenbladh. * ''waldorfstatleri'' is named after the Muppets Statler and Waldorf for the likeness of the rhachis to their heads. Taxonomy ''Geragnostus'' is very similar to ''Trinodus'' and may in future be included in that genus. In ''Trinodus'' the posterior lobe (M3) of the pygidial axis (or rhachis) is clearly shorter than the anterior and middle lobes (M1+M2) combined, while in ''Geragnostus'' it is equal or greater in length. ''Geragnostus'' is not closely related to ''Micragnostus'', because its glabella is structurally different. Species previously assigned to ''Gera ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Slump (geology
Slump may refer to: *Slump (economics), better known as a recession *Slump (food), a variety of cobbler *Slump (geology), a form of mass wasting event * "Slump" (song), by South Korean boy band Stray Kids * Slump (sports), a period in which a player or team performs below par * Sophomore slump, a failed second effort following a successful introduction *Senior slump, decreased motivation during a final year of studies *Retirement slump, the average falloff in the party's vote when the incumbent retires *Slumping, a categorical description of an area of techniques for the forming of glass by applying heat to the point where the glass becomes plastic *Dr. Slump is a Japanese manga series written and illustrated by Akira Toriyama. It was serialized in Shueisha's anthology magazine ''Weekly Shōnen Jump'' from 1980 to 1984, with the chapters collected into 18 ''tankōbon'' volumes. The series fol ..., anime and manga, character *The workability of a concrete mixture, as dete ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arthrorhachis
''Trinodus'' is a very small to small (about ) blind trilobite, a well known group of extinct marine arthropods, which lived during the Ordovician (Tremadocian to early Hirnantian), in what are now the Yukon Territories, Virginia, Italy, Czech Republic, Poland, Denmark, Sweden, Svalbard, Ireland, Scotland, Wales, Iran, Kazakhstan and China. It is one of the last of the Agnostida order to survive. Etymology ''Trinodus'' is derived from the Latin tri (three) and nodus (node). ''Arthrorhachis'' is derived from the Greek ἄρθρον (''árthron'', "joint") and ῥάχις ( ''rháchis'', meaning axis, spine, ridge or backbone). Taxonomy ''Trinodus'', ''Arthrorhachis'' and ''Geragnostus'' are closely related and it may be appropriate to assign their species to just one genus. All species in these three genera have virtually identical cephalons, but of ''T. agnostiformes'', the type species of ''Trinodus'' only one poorly preserved cephalon was known. However, relatively recen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anglagnostus
''Anglagnostus'' is a genus of trilobite in the order Agnostida, which existed in what is now Shineton, England. It was described by Howell in 1935, and the type species is ''Anglagnostus dux'', which was originally described as a species of ''Agnostus ''Agnostus'' is a genus of agnostid trilobites, belonging to the family Agnostidae, that lived during the late Middle Cambrian – early Upper Cambrian (about 506 to 492 million years ago). It is the type genus of the family Agnostidae and is sub ...''. P.A. Jell and J.M. Adrain. References Agnostidae[...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Micragnostus
''Micragnostus'' is a genus of trilobite in the order Agnostida, which existed in what is now north Wales. It was described by Howell in 1935, and the type species is ''Micragnostus calvus'', which was originally described as a species of ''Agnostus ''Agnostus'' is a genus of agnostid trilobites, belonging to the family Agnostidae, that lived during the late Middle Cambrian – early Upper Cambrian (about 506 to 492 million years ago). It is the type genus of the family Agnostidae and is sub ...'' by Lake in 1906. P.A. Jell and J.M. Adrain. References Agnostidae[...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Agnostida
Agnostida is an order of arthropod which have classically been seen as a group of highly modified trilobites, though some recent research has doubted this placement. Regardless, they appear to be close relatives as part of the Artiopoda. They are present in the Lower Cambrian fossil record along with trilobites from the Redlichiida, Corynexochida, and Ptychopariida orders, and were highly diverse throughout the Cambrian. Agnostidan diversity severely declined during the Cambrian-Ordovician transition, and the last agnostidans went extinct in the Late Ordovician. Systematics The Agnostida are divided into two suborders — Agnostina and Eodiscina — which are then subdivided into a number of families. As a group, agnostids are isopygous, meaning their pygidium is similar in size and shape to their cephalon. Most agnostid species were eyeless. The systematic position of the order Agnostida within the class Trilobita remains uncertain, and there has been continuing deb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ampyx (trilobite)
''Ampyx'' is an Ordovician-Silurian genus of Asaphid trilobites of the family Raphiophoridae. Species of ''Ampyx'' are characterized by three extended spines on the head-shield, one spine derived from each free cheek, and one spine emanating from the glabellum. Species include ''Ampyx linleyensis'' ( Lanvirn-Caradoc series). Species of ''Ampyx'' grew to an average length of . Collective behaviour Fossils of the trilobite ''Ampyx priscus'', dating back about 480 million years ago, have been recently described as clustered in lines along the ocean floor. The animals were all mature adults, and were all facing the same direction as though they had formed a conga line or a peloton. It has been suggested they line up in this manner to migrate, much as spiny lobsters migrate in single-file queues. Or perhaps they are getting together for mating. The findings suggest animal collective behaviour has very early evolutionary origins.Vannier J, Vidal M, Marchant R, El Hariri K, Kourais ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asaphida
Asaphida is a large, morphologically diverse order of trilobites found in marine strata dated from the Middle Cambrian until their extinction during the Silurian. Asaphida contains six superfamilies (Anomocaroidea, Asaphoidea, Cyclopygoidea, Dikelocephaloidea, Remopleuridoidea and Trinucleioidea), but no suborders. Asaphids comprise some 20% of described fossil trilobites. In 2020, the superfamily Trinucleoidea was proposed to be raised to an order ( Trinucleida) and removed from Asaphida. Morphology The Asaphids generally have cephalon (head) and pygidium (tail) parts similar in size, and most species have a prominent median ventral suture. Heads are often flat, and carapace furrows in the head area are often faint or not visible. Thoracic segments typically number 5 - 12, though some species have as few as two and some as many as 30. They also generally have a wide doublure, or rim, that surrounds the cephalon. This causes some specimens to be described as having a char ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
