Meniscuchus

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Meniscuchus
Temporal range: Botomian
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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
  • M. menetus Öpik, 1975 (type)
  • M. fissifrons(Rasetti, 1966) synonym Calodiscus fissifrons
  • M. helena(Walcott, 1889) synonyms Microdiscus helena, Acimetopus helena, Calodiscus helena
  • M. nanus(Palmer, 1968) synonym Calodiscus nanus
  • M. reticulata(Rasetti, 1966)

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.

Fossil Preserved remains or traces of organisms from a past geological age

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.

Arthropod phylum of animals

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.

Contents

Distribution

Description

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]

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<i>Mallagnostus</i>

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<i>Serrodiscus</i>

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.

References

  1. ↑ Sepkoski, Jack (2002). "A compendium of fossil marine animal genera (Trilobita entry)". Bulletins of American Paleontology . 364: 560. Archived from the original on 5 September 2006. Retrieved 12 January 2008.
  2. 1 2 3 Whittington, H. B. et al. Part O, Treatise on Invertebrate Paleontology. Revised, Volume 1 – Trilobita – Introduction, Order Agnostida, Order Redlichiida. 1997
  3. 1 2 3 Öpik, A.A. (1975). "Cymbric Vale Fauna of New South Wales and Early Cambrian Biostratigraphy" (PDF). BMR Bulletin. 159: 1–32.


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