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Parahughmilleria Size
''Parahughmilleria'' (meaning "near ''Hughmilleria''"Meaning opara-at ''www.dictionary.com''. Retrieved 17 July 2018.) is a genus of eurypterid, an extinct group of aquatic arthropods. Fossils of ''Parahughmilleria'' have been discovered in deposits of the Devonian and Silurian age in the United States, Canada, Russia, Germany, Luxembourg and Great Britain, and have been referred to several different species. The first fossils of ''Parahughmilleria'', discovered in the Shawangunk Mountains in 1907, were initially assigned to ''Eurypterus''. It would not be until 54 years later when ''Parahughmilleria'' would be described. ''Parahughmilleria'' is classified in the family Adelophthalmidae, the only clade in the superfamily Adelophthalmoidea. This clade was characterised by their small size, their parabolic (approximately U-shaped) carapaces and the presence of epimera (lateral "extensions" of the segment) on the seventh segment, among others. Like its relatives, ''Parahughmilleri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spine (zoology)
In a zoological context, spines are hard, needle-like anatomical structures found in both vertebrate and invertebrate species. The spines of most spiny mammals are modified hairs, with a spongy center covered in a thick, hard layer of keratin and a sharp, sometimes barbed tip. Occurrence Mammals Spines in mammals include the prickles of hedgehogs and among rodents, the quills of both New World and Old World porcupines as well as the prickly fur of spiny mice, spiny pocket mice and spiny rats. They are also found on afrotherian tenrecs, marsupial spiny bandicoots and on echidnas, of the monotremes. An ancient synapsid, '' Dimetrodon'', had extremely long spines on its backbone that were joined together with a web of skin that formed a sail-like structure. Many mammalian species, like cats and fossas, also have penile spines. The Mesozoic eutriconodont mammal ''Spinolestes'' already displayed spines similar to those of modern spiny mice. Fish Spines are found in the rays o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adelophthalmus
''Adelophthalmus'' is a genus of eurypterid, an extinct group of aquatic arthropods. Fossils of ''Adelophthalmus'' have been discovered in deposits ranging in age from the Early Devonian to the Early Permian, which makes it the longest lived of all known eurypterid genera, with a total temporal range of over 120 million years. ''Adelopththalmus'' was the final genus of the Eurypterina suborder of eurypterids and consisted the only known genus of swimming eurypterids from the Middle Devonian until its extinction during the Permian, after which the few surviving eurypterids were all walking forms of the suborder Stylonurina. Fossils of ''Adelophthalmus'' have been described from four continents; North America, Europe, Asia and Australia, which indicates that ''Adelophthalmus'' might have had a nearly cosmopolitan (worldwide) distribution, one of few eurypterid genera to achieve one besides potentially ''Pterygotus''. The territorial expansion of ''Adelophthalmus'' had begun early, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Operculum (animal)
An operculum is an anatomical feature, a stiff structure resembling a lid or a small door that opens and closes, and thus controls contact between the outside world and an internal part of an animal. Examples include: * An operculum (gastropod), a single lid that (in its most complete form) closes the aperture of the shell when the animal is retracted, and thus protects the internal soft parts of the animal that are not completely covered by the shell. The operculum lies on the top rear part of the foot. When the foot is retracted, the operculum is rotated 180° and closes the shell. * An operculum (fish), a flap that covers the gills in bony fishes and chimaeras. * The cover that rapidly opens a cnida of a cnidarian such as a jellyfish or a sea anemone. The lid may be a single hinged flap or three hinged flaps arranged like slices of pie. * In insects, the operculum is the name for one or more lids covering the tympanal cavity. A subgenital operculum is exhibited in phasmoidea an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atlantic Geology
''Atlantic Geology'' is a peer-reviewed scientific journal covering the geology of Atlantic Canada and related areas. It is the only regional geology journal in Canada and publishes papers, notes and discussions on original research, and review papers. It was established in 1965 and since 1986 has been published by the Atlantic Geoscience Society with digital publishing assistance from the University of New Brunswick. The journal was one of the first all-digital publications in Canada.Barr, S (2014). The history of the Atlantic Geology journal: the first 50 years. Keynote talk at the Atlantic Geoscience Society annual colloquium, Wolfville, Nova Scotia, February 2014. History The journal was established in 1965 as ''Maritime Sediments'' and later renamed ''Maritime Sediments and Atlantic Geology'' before obtaining its current name. The founding editor-in-chief was Daniel Stanley (Dalhousie University). Subsequent editors have included Deryck Laming, Bernard Pelletier, George Pajari ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tergite
A ''tergum'' (Latin for "the back"; plural ''terga'', associated adjective tergal) is the dorsal ('upper') portion of an arthropod segment other than the head. The anterior edge is called the 'base' and posterior edge is called the 'apex' or 'margin'. A given tergum may be divided into hardened plates or sclerites commonly referred to as tergites. In a thoracic segment, for example, the tergum may be divided into an anterior notum and a posterior scutellum. Lateral extensions of a tergite are known as paranota (Greek for "alongside the back") or ''carinae'' (Latin for "keel"), exemplified by the flat-backed millipedes of the order Polydesmida. Kinorhynchs have tergal and sternal plates too, though seemingly not homologous with those of arthropods. Tergo-tergal is a stridulatory mechanism in which fine spines of the abdominal tergites are rubbed together to produce sound. This process is known as abdominal telescoping. Examples File:Andrena spiraeana abdomen.jpg , Abdominal t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Telson
The telson () is the posterior-most division of the body of an arthropod. Depending on the definition, the telson is either considered to be the final segment of the arthropod body, or an additional division that is not a true segment on account of not arising in the embryo from teloblast areas as other segments. It never carries any appendages, but a forked "tail" called the caudal furca may be present. The shape and composition of the telson differs between arthropod groups. Crustaceans In lobsters, shrimp and other decapods, the telson, along with the uropods, forms the tail fan. This is used as a paddle in the caridoid escape reaction ("lobstering"), whereby an alarmed animal rapidly flexes its tail, causing it to dart backwards. Krill can reach speeds of over 60 cm per second by this means. The trigger time to optical stimulus is, in spite of the low temperatures, only 55 milliseconds. In the Isopoda and Tanaidacea (superorder Peracarida), the last abdominal b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metastoma
The metastoma is a ventral single plate located in the opisthosoma of non-arachnid dekatriatan chelicerates such as eurypterids, chasmataspidids and the genus ''Houia''. The metastoma located between the base of 6th prosomal appendage pair and may had functioned as part of the animal's feeding structures. It most likely represented a fused appendage pair originated from somite 7 (first opisthosomal segment), thus homologous to the chilaria of horseshoe crab and 4th walking leg pair of sea spider. In eurypterids, the plate was typically cordate (heart-shaped) in shape, though differed in shape in some genera, such as ''Megalograptus ''Megalograptus'' is a genus of eurypterid, an extinct group of aquatic arthropods. Fossils of ''Megalograptus'' have been recovered in deposits of Katian (Late Ordovician) age in North America. The genus contains five species: ''M. alveolatu ...''. References Chelicerate anatomy Dekatriata {{Chelicerata-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Compound Eyes
A compound eye is a visual organ found in arthropods such as insects and crustaceans. It may consist of thousands of ommatidia, which are tiny independent photoreception units that consist of a cornea, lens, and photoreceptor cells which distinguish brightness and color. The image perceived by this arthropod eye is a combination of inputs from the numerous ommatidia, which are oriented to point in slightly different directions. Compared with single-aperture eyes, compound eyes have poor image resolution; however, they possess a very large view angle and the ability to detect fast movement and, in some cases, the polarization of light. Because a compound eye is made up of a collection of ommatidia, each with its own lens, light will enter each ommatidium instead of using a single entrance point. The individual light receptors behind each lens are then turned on and off due to a series of changes in the light intensity during movement or when an object in moving, creating a flick ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carapace
A carapace is a Dorsum (biology), dorsal (upper) section of the exoskeleton or shell in a number of animal groups, including arthropods, such as crustaceans and arachnids, as well as vertebrates, such as turtles and tortoises. In turtles and tortoises, the underside is called the plastron. Crustaceans In crustaceans, the carapace functions as a protective cover over the cephalothorax (i.e., the fused head and thorax, as distinct from the abdomen behind). Where it projects forward beyond the eyes, this projection is called a rostrum (anatomy), rostrum. The carapace is Calcification, calcified to varying degrees in different crustaceans. Zooplankton within the phylum Crustacea also have a carapace. These include Cladocera, ostracods, and Isopoda, isopods, but isopods only have a developed "cephalic shield" carapace covering the head. Arachnids In arachnids, the carapace is formed by the fusion of prosomal tergites into a single Plate (animal anatomy), plate which carries the e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ontogeny
Ontogeny (also ontogenesis) is the origination and development of an organism (both physical and psychological, e.g., moral development), usually from the time of fertilization of the egg to adult. The term can also be used to refer to the study of the entirety of an organism's lifespan. Ontogeny is the developmental history of an organism within its own lifetime, as distinct from phylogeny, which refers to the evolutionary history of a species. Another way to think of ontogeny is that it is the process of an organism going through all of the developmental stages over its lifetime. The developmental history includes all the developmental events that occur during the existence of an organism, beginning with the changes in the egg at the time of fertilization and events from the time of birth or hatching and afterward (i.e., growth, remolding of body shape, development of secondary sexual characteristics, etc.). While developmental (i.e., ontogenetic) processes can influence sub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biology Letters
''Biology Letters'' is a peer-reviewed, biological, scientific journal published by the Royal Society. It focuses on the rapid publication of short high quality research articles, reviews and opinion pieces across the biological sciences. ''Biology Letters'' has an average turnaround time of twenty four days from submission to a first decision. The editor-in-chief is Professor David Beerling FRS (University of Sheffield) who is supported by an international Editorial Board of practising scientists. Contents and themes As well as the conventional, short research articles, ''Biology Letters'' has recently published Special Features and Mini Series. While Special Features are a collection of up to 20 articles on a specific theme and published across multiple issues, Mini Series include up to six articles that are published in one issue. Examples of topics in these formats include ocean acidification, fossils, extinction, enhanced rock weathering and the evolutionary ecology of sp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
