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Chasmataspis
''Chasmataspis'' is a genus of chasmataspidid, a group of extinct aquatic chelicerate arthropods. It was found in the Early Ordovician deposits of Tennessee, USA. Morphology Just like other chasmataspidids, the body of ''Chasmataspis'' compose of a prosoma and a 13-segmented opisthosoma, with the latter subdivided into a 4-segmented preabdomen and a 9-segmented postabdomen. Dorsal to the carapace were pairs of ridges, lateral eyes and median ocelli. ''Chasmataspis'' characterized by a semicircular carapace (prosomal dorsal shield) with pointed genal spines and preabdomen with fused body segments. Rows of tubercles and spines run through the axial and lateral regions of opisthosoma. The body terminated with a spine-like telson. There is no body fossils of ''Chasmataspis'' with unambiguous appendages being discovered. The only evidence were 2 specimens of disarticulated, claw A claw is a curved, pointed appendage found at the end of a toe or finger in most amniotes (mam ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chasmataspidid
Chasmataspidids, sometime referred to as chasmataspids, are a group of extinct chelicerate arthropods that form the order Chasmataspidida. Chasmataspidids are probably related to horseshoe crabs (Xiphosura) and/or sea scorpions (Eurypterida), with more recent studies suggest that they form a clade (Dekatriata) with Eurypterida and Arachnida. Chasmataspidids are known sporadically in the fossil record through to the mid-Devonian, with possible evidence suggesting that they were also present during the late Cambrian. Chasmataspidids are most easily recognised by having an opisthosoma divided into a wide forepart (preabdomen) and a narrow hindpart (postabdomen) each comprising 4 and 9 segments respectively. There is some debate about whether they form a natural (i.e. monophyletic) group. Distribution Chasmataspidids survived at least since Ordovician to mid-Devonian in age. As of 2019, most chasmataspidids (with a total of 9 species) are known from the Devonian strata, while the p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chasmataspididae
''Chasmataspis'' is a genus of chasmataspidid, a group of extinct aquatic chelicerate arthropods. It was found in the Early Ordovician deposits of Tennessee, USA. Morphology Just like other chasmataspidids, the body of ''Chasmataspis'' compose of a prosoma and a 13-segmented opisthosoma, with the latter subdivided into a 4-segmented preabdomen and a 9-segmented postabdomen. Dorsal to the carapace were pairs of ridges, lateral eyes and median ocelli. ''Chasmataspis'' characterized by a semicircular carapace (prosomal dorsal shield) with pointed genal spines and preabdomen with fused body segments. Rows of tubercles and spines run through the axial and lateral regions of opisthosoma. The body terminated with a spine-like telson. There is no body fossils of ''Chasmataspis'' with unambiguous appendages being discovered. The only evidence were 2 specimens of disarticulated, claw A claw is a curved, pointed appendage found at the end of a toe or finger in most amniotes (mam ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chasmataspis
''Chasmataspis'' is a genus of chasmataspidid, a group of extinct aquatic chelicerate arthropods. It was found in the Early Ordovician deposits of Tennessee, USA. Morphology Just like other chasmataspidids, the body of ''Chasmataspis'' compose of a prosoma and a 13-segmented opisthosoma, with the latter subdivided into a 4-segmented preabdomen and a 9-segmented postabdomen. Dorsal to the carapace were pairs of ridges, lateral eyes and median ocelli. ''Chasmataspis'' characterized by a semicircular carapace (prosomal dorsal shield) with pointed genal spines and preabdomen with fused body segments. Rows of tubercles and spines run through the axial and lateral regions of opisthosoma. The body terminated with a spine-like telson. There is no body fossils of ''Chasmataspis'' with unambiguous appendages being discovered. The only evidence were 2 specimens of disarticulated, claw A claw is a curved, pointed appendage found at the end of a toe or finger in most amniotes (mam ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chasmataspis Line
''Chasmataspis'' is a genus of chasmataspidid, a group of extinct aquatic chelicerate arthropods. It was found in the Early Ordovician deposits of Tennessee, USA. Morphology Just like other chasmataspidids, the body of ''Chasmataspis'' compose of a prosoma and a 13-segmented opisthosoma, with the latter subdivided into a 4-segmented preabdomen and a 9-segmented postabdomen. Dorsal to the carapace were pairs of ridges, lateral eyes and median ocelli. ''Chasmataspis'' characterized by a semicircular carapace (prosomal dorsal shield) with pointed genal spines and preabdomen with fused body segments. Rows of tubercles and spines run through the axial and lateral regions of opisthosoma. The body terminated with a spine-like telson. There is no body fossils of ''Chasmataspis'' with unambiguous appendages being discovered. The only evidence were 2 specimens of disarticulated, claw-bearing appendages discovered from the same stratum In geology and related fields, a stratum ( : st ... [...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] |
Natural History Museum Bern
The Natural History Museum of Bern (german: Naturhistorisches Museum Bern) is a museum in Bern, Switzerland. In its teaching and research it cooperates closely with the University of Bern.In Bern beliebt - auf der ganzen Welt beachtet It is visited by around 131,000 people yearly. History The museum is owned by the Burgergemeinde of Bern, so it is also known as . It was officially founded in 1832. It is located on Bernastrasse, in the Kirchenfeld , in a building that was erected between 1932 and 1934, opened in 1936 and expanded several times since th ...[...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stratum
In geology and related fields, a stratum ( : strata) is a layer of rock or sediment characterized by certain lithologic properties or attributes that distinguish it from adjacent layers from which it is separated by visible surfaces known as either '' bedding surfaces'' or ''bedding planes''.Salvador, A. ed., 1994. ''International stratigraphic guide: a guide to stratigraphic classification, terminology, and procedure. 2nd ed.'' Boulder, Colorado, The Geological Society of America, Inc., 215 pp. . Prior to the publication of the International Stratigraphic Guide, older publications have defined a stratum as either being either equivalent to a single bed or composed of a number of beds; as a layer greater than 1 cm in thickness and constituting a part of a bed; or a general term that includes both ''bed'' and ''lamina''.Neuendorf, K.K.E., Mehl, Jr., J.P., and Jackson, J.A. , eds., 2005. ''Glossary of Geology'' 5th ed. Alexandria, Virginia, American Geological Institute. 779 pp. . ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chela (organ)
A chela ()also called a claw, nipper, or pinceris a pincer (biology), pincer-like organ at the end of certain limbs of some arthropods. The name comes from Ancient Greek , through New Latin '. The plural form is chelae. Legs bearing a chela are called chelipeds. Another name is ''claw'' because most chelae are curved and have a sharp point like a claw. Chelae can be present at the tips of arthropod legs as well as their pedipalps. Chelae are distinct from spider chelicerae in that they do not contain venomous glands and cannot distribute venom. See also * Pincer (biology) * Pincer (tool) References Arthropod anatomy {{Arthropod-anatomy-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Appendage
An appendage (or outgrowth) is an external body part, or natural prolongation, that protrudes from an organism's body. In arthropods, an appendage refers to any of the homologous body parts that may extend from a body segment, including antennae, mouthparts (including mandibles, maxillae and maxillipeds), gills, locomotor legs ( pereiopods for walking, and pleopods for swimming), sexual organs (gonopods), and parts of the tail (uropods). Typically, each body segment carries one pair of appendages. An appendage which is modified to assist in feeding is known as a maxilliped or gnathopod. In vertebrates, an appendage can refer to a locomotor part such as a tail, fins on a fish, limbs (legs, flippers or wings) on a tetrapod; exposed sex organ; defensive parts such as horns and antlers; or sensory organs such as auricles, proboscis ( trunk and snout) and barbels. Appendages may become ''uniramous'', as in insects and centipedes, where each appendage comprises a single ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fossil
A fossil (from Classical Latin , ) 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 and DNA remnants. The totality of fossils is known as the ''fossil record''. Paleontology is the study of fossils: their age, method of formation, and evolutionary significance. Specimens are usually considered to be fossils if they are over 10,000 years old. The oldest fossils are around 3.48 billion years old to 4.1 billion years old. Early edition, published online before print. The observation in the 19th century that certain fossils were associated with certain rock strata led to the recognition of a geological timescale and the relative ages of different fossils. The development of radiometric dating techniques in the early 20th century allowed scientists to quantitatively measure the ... [...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] |
Ordovician
The Ordovician ( ) is a geologic period and System (geology), system, the second of six periods of the Paleozoic Era (geology), Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period million years ago (Mya) to the start of the Silurian Period Mya. The Ordovician, named after the Celtic Britons, Welsh tribe of the Ordovices, was defined by Charles Lapworth in 1879 to resolve a dispute between followers of Adam Sedgwick and Roderick Murchison, who were placing the same Rock (geology), rock beds in North Wales in the Cambrian and Silurian systems, respectively. Lapworth recognized that the fossil fauna in the disputed Stratum, strata were different from those of either the Cambrian or the Silurian systems, and placed them in a system of their own. The Ordovician received international approval in 1960 (forty years after Lapworth's death), when it was adopted as an official period of the Paleozoic Era by the International Union of Geological Sciences, Intern ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
