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Houia
''Houia'' is an extinct genus of dekatriatan, a clade of chelicerate arthropods. Fossils of ''Houia'' have been discovered in deposits of the Early Devonian period in Guangxi and Yunnan, both in China. The genus contains two species: ''H. guangxiensis'', from the Pragian to Emsian epoch of Guangxi; and ''H. yueya'', the type species, from the Lochkovian epoch of Yunnan. The name of the genus is derived from the Chinese character 鲎 (''hòu''), meaning "horseshoe crab". ''Houia yueya'' was originally described as a species of the xiphosuran (horseshoe crab) genus '' Kasibelinurus'' (''Kasibelinurus yueya'') in 2013, with its narrow opisthosoma (the trunk section) being misinterpreted as incompletely preserved (lacking lateral regions). The species name ''yueya'' comes from the Chinese characters 月 (''yuè'', meaning "Moon") and 牙 (''yá'', meaning "crescent"), referring to the crescentic shape of its carapace (the dorsal plate of the prosoma or head). ''H. yueya'' was rede ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dekatriata
Dekatriata is a clade of planatergan chelicerates including the groups Arachnida, Chasmataspidida, Eurypterid Eurypterids, often informally called sea scorpions, are a group of extinct marine arthropods that form the Order (biology), order Eurypterida. The earliest known eurypterids date to the Darriwilian stage of the Ordovician period, 467.3 Myr, mil ...a and additionally two stem-genera '' Winneshiekia'' and '' Houia''. Dekatriata is defined by an opisthosoma with 13 segments as groundplan (the number proposed to be secondarily reduced in most arachnid orders) and fused, plate-like appendages on the first opisthosomal segment (somite VII). References Middle Ordovician first appearances {{Chelicerata-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kasibelinurus
''Kasibelinurus'' (meaning "sibling of dart tail" for its perceived relation to ''Belinurus'' at the time) is a genus of xiphosuran from the Devonian. It is part of the family Kasibelinuridae. The type species and only species of ''Kasibelinurus'' is ''K. amicorum'' (derived from Latin word ''amicus'' meaning 'friend'). The type species was set by J. Pickett in 1993. Description The genus ''Kasibelinurus'' was described by Pickett as having "Ophthalmic ridges effaced; precardiac field defined by anterior prolongations of the cardiac furrows; opisthosomal pleurae with distinct inner and outer zones." The same source later states that ''Kasibelinurus'' had a telson with restricted movement based on the shape of the opisthosoma. See Also '' Patesia'' - genus of horseshoe crabs formerly thought to be of Kasibelinurus ''Houia ''Houia'' is an extinct genus of dekatriatan, a clade of chelicerate arthropods. Fossils of ''Houia'' have been discovered in deposits of the Early ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lochkovian
The Lochkovian is one of three faunal stages in the Early Devonian Epoch. It lasted from 419.2 ± 3.2 million years ago to 410.8 ± 2.8 million years ago. It marked the beginning of the Devonian Period, and was followed by the Pragian Stage. It is named after the village of Lochkov in the Czech Republic, now part of the city of Prague. The GSSP is located within the Lochkow Formation at the Klonk Section in Prague. In North America the Lochkovian Stage is represented by Gedinnian or Helderbergian time. References Lochkovian, Early Devonian {{geochronology-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epoch (geology)
The geologic time scale or geological time scale (GTS) is a representation of time based on the rock record of Earth. It is a system of chronological dating that uses chronostratigraphy (the process of relating strata to time) and geochronology (a scientific branch of geology that aims to determine the age of rocks). It is used primarily by Earth scientists (including geologists, paleontologists, geophysicists, geochemists, and paleoclimatologists) to describe the timing and relationships of events in geologic history. The time scale has been developed through the study of rock layers and the observation of their relationships and identifying features such as lithologies, paleomagnetic properties, and fossils. The definition of standardised international units of geological time is the responsibility of the International Commission on Stratigraphy (ICS), a constituent body of the International Union of Geological Sciences (IUGS), whose primary objective is to precis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geological Magazine
The ''Geological Magazine'' is a peer-reviewed scientific journal established in 1864, covering the earth sciences. It publishes original scientific research papers on geological topics. The journal is published bimonthly by Cambridge University Press. External links * Full online archiveIssues 1864–1922online available in Biodiversity Heritage Library The Biodiversity Heritage Library (BHL) is the world’s largest open-access digital library for biodiversity literature and archives. BHL operates as a worldwide consortium of natural history, botanical, research, and national libraries working ... English-language journals Publications established in 1864 Geology journals Cambridge University Press academic journals Bimonthly journals {{geology-journal-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prosoma
The cephalothorax, also called prosoma in some groups, is a tagma of various arthropods, comprising the head and the thorax fused together, as distinct from the abdomen behind. (The terms ''prosoma'' and ''opisthosoma'' are equivalent to ''cephalothorax'' and ''abdomen'' in some groups. The terms ''prosoma'' and ''opisthosoma'' may be preferred by some researchers in cases such as arachnids, where there is neither fossil nor embryonic evidence animals in this class have ever had separate heads and thoraxes, and where the ''opisthosoma'' contains organs atypical of a true ''abdomen'', such as a heart and respiratory organs.) The word ''cephalothorax'' is derived from the Greek words for head (, ') and thorax (, '). This fusion of the head and thorax is seen in chelicerates and crustaceans; in other groups, such as the Hexapoda (including insects), the head remains free of the thorax. In horseshoe crabs and many crustaceans, a hard shell called the carapace covers the cephalothorax. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anatomical Terms Of Location
Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position provides a definition of what is at the front ("anterior"), behind ("posterior") and so on. As part of defining and describing terms, the body is described through the use of anatomical planes and axes. The meaning of terms that are used can change depending on whether a vertebrate is a biped or a quadruped, due to the difference in the neuraxis, or if an invertebrate is a non-bilaterian. A non-bilaterian has no anterior or posterior surface for example but can still have a descriptor used such as proximal or distal in relation to a body part that is nearest to, or furthest from its middle. International organisations have determined vocabularies that are often used as standards for subdisciplines of anatomy. For example, '' Termi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carapace
A carapace is a 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. In botany, a carapace refers to the hard outer cover of a seed which protects the inner embryo. 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. The carapace is calcified to varying degrees in different crustaceans. Zooplankton within the phylum Crustacea also have a carapace. These include Cladocera, ostracods, and 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 pl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Moon
The Moon is Earth's only natural satellite. It Orbit of the Moon, orbits around Earth at Lunar distance, an average distance of (; about 30 times Earth diameter, Earth's diameter). The Moon rotation, rotates, with a rotation period (lunar day) that is synchronized to its orbital period (Lunar month#Synodic month, lunar month) of 29.5 Earth days. This is the product of Earth's gravitation having tidal forces, tidally pulled on the Moon until one part of it stopped rotating away from the near side of the Moon, near side, making always the same lunar surface face Earth. Conversley, the gravitational pull of the Moon, on Earth, is the main driver of Earth's tides. In geophysical definition of planet, geophysical terms, the Moon is a planetary-mass object or satellite planet. Its mass is 1.2% that of the Earth, and its diameter is , roughly one-quarter of Earth's (about as wide as the contiguous United States). Within the Solar System, it is the List of Solar System objects by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Opisthosoma
The opisthosoma is the posterior part of the body in some arthropods, behind the prosoma ( cephalothorax). It is a distinctive feature of the subphylum Chelicerata (arachnids, horseshoe crabs and others). Although it is similar in most respects to an abdomen (and is often referred to as such), the opisthosoma is differentiated by its inclusion of the respiratory organs ( book lungs or book gills) and the heart. Segments The number of segments and appendages on the opisthosoma vary. Scorpions have 13, but the first is only seen during its embryological development. Other arachnids have fewer; harvestmen, for instance, have only ten. In general, appendages are absent or reduced, although in horseshoe crabs they persist as large plate-like limbs, called opercula or branchiophores, bearing the book gills, and that function in locomotion and gas exchange. In most chelicerates the opisthosomal limbs are greatly reduced and persist only as specialized structures, such as the silk- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Xiphosuran
Xiphosura (; , in reference to its sword-like telson) is an order of arthropods related to arachnids. They are more commonly known as horseshoe crabs (a name applied more specifically to the only extant family, Limulidae). They first appeared in the Hirnantian (Late Ordovician). Currently, there are only four living species. Xiphosura contains one suborder, Xiphosurida, and several stem-genera. The group has hardly changed in appearance in hundreds of millions of years; the modern horseshoe crabs look almost identical to prehistoric genera and are considered to be living fossils. The most notable difference between ancient and modern forms is that the abdominal segments in present species are fused into a single unit in adults. Xiphosura were historically placed in the class Merostomata, although this term was intended to encompass also the eurypterids, whence it denoted what is now thought to be an unnatural (paraphyletic) group (although this is a grouping recovered in some rece ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
