Meniscuchus | |
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Scientific classification | |
Kingdom: | Animalia |
Phylum: | Arthropoda |
Class: | Trilobita |
Order: | Agnostida |
Suborder: | Eodiscina |
Superfamily: | Eodiscoidea |
Family: | Weymouthiidae |
Genus: | Meniscuchus Öpik, 1975 |
species | |
Meniscuchus is an extinct genus from a well-known class of fossil marine arthropods, the trilobites. It lived during the Botomian stage, [1] which lasted from approximately 522 to 516 million years ago. This faunal stage was part of the Cambrian Period. Meniscuchus has been found in the USA (Alaska, New York), Canada (Newfoundland, Quebec), Russia (Siberian Platform, Gorno-Altayskaya) and Australia (New South Wales). [2]
A genus is a taxonomic rank used in the biological classification of living and fossil organisms, as well as viruses, in biology. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclature, the genus name forms the first part of the binomial species name for each species within the genus.
A fossil is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved in amber, hair, petrified wood, oil, coal, and DNA remnants. The totality of fossils is known as the fossil record.
An arthropod is an invertebrate animal having an exoskeleton, a segmented body, and paired jointed appendages. Arthropods form the phylum Euarthropoda, which includes insects, arachnids, myriapods, and crustaceans. The term Arthropoda as originally proposed refers to a proposed grouping of Euarthropods and the phylum Onychophora. Arthropods are characterized by their jointed limbs and cuticle made of chitin, often mineralised with calcium carbonate. The arthropod body plan consists of segments, each with a pair of appendages. The rigid cuticle inhibits growth, so arthropods replace it periodically by moulting. Arthopods are bilaterally symmetrical and their body possesses an external skeleton. Some species have wings.
Like all Eodiscina, the headshield (or cephalon) and tailshield (or pygidium) are approximately equal in size. Like all Weymouthiidae, Meniscuchus is eyeless and lacks free cheeks. The axis of the cephalon (or glabella) is wide at its base (that is, where it would touch the thorax) and is rounded at the front, where it touches the border furrow. The glabella is divided by two furrows crossing the glabella, creating a frontal lobe (L4) more than twice as long (along the axis) as its narrow neighbour (L3). Further lobes (L2 and L1) may be suggested by a faint dent in the furrow defining the outline of the glabella. At the back the glabella is terminated by a narrow occipital ring (L0), extended backwards at midline with its margin a semicircle. The cephalic border is almost as wide as L4, but is only half as wide laterally while becoming slightly wider again further back. Thorax probably with three segments. [3] Its pygidium is relatively long. Its axis is tapering and reaching the border furrow at midline, and is deeply segmented with 4 to 10 axial rings. The pleural areas are unfurrowed. The border of the pygidium is uniformly narrow. The doublure is wide and almost vertical. [2]
Paradoxides is a genus of large to very large trilobites found throughout the world during the Mid Cambrian period. One record-breaking specimen of Paradoxides davidis is 37 cm (15 in). It has a semicircular head, free cheeks each ending with a long, narrow, recurved spine, and sickle-shaped eyes, providing almost 360° view, but only in the horizontal plane. Its elongated trunk was composed of 19-21 segments and was adorned with longish, recurved lateral spines. Its pygidium was comparatively small. Paradoxides is a characteristic Middle Cambrian trilobite of the 'Atlantic' (Avalonian) fauna. Avalonian rocks were deposited near a small continent called Avalonia in the Paleozoic Iapetus Ocean. Avalonian beds are now in a narrow strip along the East Coast of North America, and in Europe.
Acidiscus is an extinct genus of eodiscinid agnostid trilobites. It lived during the Botomian stage of the Cambrian period.
Acimetopus is a genus of trilobites that lived during the Botomian stage.
Ninadiscus is an extinct genus from a well-known class of fossil marine arthropods, the trilobites. It lived during the Botomian.
Dicerodiscus is an extinct genus from a well-known class of fossil marine arthropods, the trilobites. It lived during the early part of the Botomian stage, in China. Four species have been assigned to it. Dicerodiscus is unique for an eodiscoid in having conspicuous and curved spines that are attached anteriorly, and at their base are directed outward perpendicular to the midline, before gradually bending further backwards.
Olenelloides armatus is an extinct, small sized olenelloid redlichiid trilobite arthropod. It lived during the later part of the Botomian stage, which lasted from approximately 524 to 518.5 million years ago. This faunal stage was part of the Cambrian Period. The most conspicuous feature is the hexagonal head shield that carries 6 ray-like spines..
Wanneria is an extinct genus from a well-known class of fossil marine arthropods, the trilobites. It lived during the later part of the Botomian stage, which lasted from approximately 524 to 518.5 million years ago. This faunal stage was part of the Cambrian Period. Wanneria walcottana is the only known species in this genus.
Acmarhachis is a genus of trilobite in the order Agnostida, which lived in what are now Australia, Canada, China (Anhui), Kazakhstan, Russia (Kharaulakh), and the US. It was described by Resser in 1938, and the type species is Acmarhachis typicalis.
Conocoryphe is a genus of primarily eyeless trilobites belonging to the family Conocoryphidae. They lived during the Middle Cambrian period, about 505 million years ago. These arthropods lived on the sea bottom (epifaunal) and lived off dead particulate organic matter.
Odontochile is a genus of trilobites in the order Phacopida, family Dalmanitidae.
The Bristoliinae is an extinct subfamily of trilobites, fossil marine arthropods, with species of small to average size. Species belonging to this subfamily lived during the Botomian and Toyonian stage (Olenellus-zone), 522-513 million years ago, in the former continent of Laurentia, including what are today Mexico, the Appalachian Mountains and the south-western United States, and Canada.
Mallagnostus is an extinct genus from a well-known class of fossil marine arthropods, the trilobites. It lived during the upper Lower Cambrian, with remains found in USA, Canada (Newfoundland), Spain, England, Russia, Mongolia, and the lower Middle Cambrian according to fossils from China and Russia (Yakutia).
Diplorrhina is a genus of trilobites, a well known class of extinct marine arthropods. It lived during the early Middle Cambrian in what are now the Czech Republic and the North Siberian plateau. Like all agnostina it has a headshield (or cephalon and tailshield (or pygidium of approximately the same shape and size, and two thorax segments. Like other members of the Peronopsidae family, it lacks a furrow connecting the furrow surrounding the central raise area of the cephalon and the furrow that defines the border of the cephalon. Both the cephalon and the pygidium lack spines. It is difficult to distinguish from many other peronopsids.
Geragnostus is a genus of very small agnostid trilobites whose fossils are found Ordovician-aged marine strata from Eurasia, North America and Argentina.
Toragnostus is a genus of trilobites restricted to the late Middle Cambrian. Its remains have been found in the United States, Greenland, Denmark, China, Sweden, the Russian Federation, and Kazakhstan. Its headshield and tailshield are almost completely effaced and it has two thorax segments.
Ovatoryctocara is a genus of small corynexochid trilobites from the Cambrian, that lived in what now are Siberia, China, Greenland and Canada (Newfoundland). Ovatoryctocara can be recognised by the combination of the following characters: the central raised area of the cephalon is approximately cylindrical and has two rows of four triangular or round pits. The thorax only has 5 or 6 segments. The tailshield has an axis of 6 to 12 rings, the pleural furrows are well developed and the border is absent or narrow as a hair.
Tannudiscus is an extinct genus from a well-known class of fossil marine arthropods, the trilobites. It lived during the upper Lower Cambrian, with remains found in Canada (Newfoundland), China (Gansu), The United Kingdom (England), and the Russian Federation.
Anabaraspis is a genus of redlichiid trilobite. A. splendens occurs in the uppermost Lower Cambrian and lowest Middle Cambrian of Russia. In Anabaraspis there is a long area in front of the glabella which is not differentiated in a border and a preglabellar field. This is a unique character in the family Paradoxididae. The frontal lobe of the central raised area of the headshield is slightly pointed, rather than rounded or truncate, a character shared with Plutonides, though, in Plutonides it hangs over the short anterior border.
Plutonides is a genus of trilobite, an extinct group of marine arthropods. Species occur in the middle Middle Cambrian of Russia (Siberia), Mongolia, England and Wales, Sweden, eastern Canada, and the Czech Republic. The frontal lobe of the central raised area of the headshield overhangs the short frontal border and it is slightly pointed, rather than rounded or truncate. This character is shared with Anabaraspis, but in Anabaraspis there is a wide area in front of the glabella without a differentiated border and preglabellar field.
Serrodiscus is an extinct genus from a well-known class of fossil marine arthropods, the trilobites. It has been collected from the Lower Cambrian of Canada, Germany (Silesia), Poland, Russia, the United Kingdom (Wales) and the United States. It is named for the spines on the ventral side of the tailshield (or pygidium, which give it a serrated impression.
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