Plesioelasmosaurus Walker
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Plesioelasmosaurus Walker
''Plesioelasmosaurus'' is an extinct genus of elasmosaurid plesiosaur from the Late Cretaceous (middle Cenomanian) Greenhorn Limestone of Kansas, United States. The genus contains a single species, ''P. walkeri'', known from a partial skeleton. Discovery and naming The holotype specimen, UNSM 50134, was discovered by Joe Purzer, an oil field geologist, in 1931 near the town of Holyrood, Kansas. He notified George F. Sternberg and Myrl Vincent Walker, and the excavation of the specimen commenced later in the year. It was collected over a period of ten days in October 1931. The specimen became known as the 'Holyrood elasmosaur' and was eventually sold to the University of Nebraska State Museum in 1935, where it was prepared and placed into storage. Everhart (2007) noted that Harold Ehler used photographs of the holotype to identify the type locality, but no further remains of ''Plesioelasmosaurus'' resulted from Ehler's discovery. The holotype consists of both ilia, par ...
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Late Cretaceous
The Late Cretaceous (100.5–66 Ma) is the more recent of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', the Latin word for the white limestone known as chalk. The chalk of northern France and the white cliffs of south-eastern England date from the Cretaceous Period. Climate During the Late Cretaceous, the climate was warmer than present, although throughout the period a cooling trend is evident. The tropics became restricted to equatorial regions and northern latitudes experienced markedly more seasonal climatic conditions. Geography Due to plate tectonics, the Americas were gradually moving westward, causing the Atlantic Ocean to expand. The Western Interior Seaway divided North America into eastern and western halves; Appalachia and Laramidia. India maintained a northward course towards Asia. In the Southern Hemisphere, Aus ...
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Cervical Vertebrae
In tetrapods, cervical vertebrae (: vertebra) are the vertebrae of the neck, immediately below the skull. Truncal vertebrae (divided into thoracic and lumbar vertebrae in mammals) lie caudal (toward the tail) of cervical vertebrae. In sauropsid species, the cervical vertebrae bear cervical ribs. In lizards and saurischian dinosaurs, the cervical ribs are large; in birds, they are small and completely fused to the vertebrae. The vertebral transverse processes of mammals are homologous to the cervical ribs of other amniotes. Most mammals have seven cervical vertebrae, with the only three known exceptions being the manatee with six, the two-toed sloth with five or six, and the three-toed sloth with nine. In humans, cervical vertebrae are the smallest of the true vertebrae and can be readily distinguished from those of the thoracic or lumbar regions by the presence of a transverse foramen, an opening in each transverse process, through which the vertebral artery, verteb ...
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Late Cretaceous Plesiosaurs Of North America
Late or LATE may refer to: Everyday usage * Tardy, or late, not being on time * Late (or the late) may refer to a person who is dead Music * ''Late'' (The 77s album), 2000 * Late (Alvin Batiste album), 1993 * Late!, a pseudonym used by Dave Grohl on his ''Pocketwatch'' album * Late (rapper), an underground rapper from Wolverhampton * "Late", a song by Kanye West from ''Late Registration'' Other uses * Late (Tonga), an uninhabited volcanic island southwest of Vavau in the kingdom of Tonga * "Late" (''The Handmaid's Tale''), a television episode * LaTe, Oy Laivateollisuus Ab, a defunct shipbuilding company * Limbic-predominant age-related TDP-43 encephalopathy, a proposed form of dementia * Local-authority trading enterprise, a New Zealand business law * Local average treatment effect, a concept in econometrics * Late, a synonym for ''cooler'' in stellar classification See also * * * ''Lates'', a genus of fish in the lates perch family * Later (other) Later may refer ...
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Elasmosauridae
Elasmosauridae, often called elasmosaurs or elasmosaurids, is an extinct family of plesiosaurs that lived from the Hauterivian stage of the Early Cretaceous to the Maastrichtian stage of the Late Cretaceous period (c. 130 to 66 mya). The taxon was initially erected in 1869 by Edward Drinker Cope to include the type genus '' Elasmosaurus'' with the related '' Cimoliasaurus'', although he did not argued in detail why. Over the following years, many authors recognized this classification on the basis of predominantly postcranial features, becoming one of the three groups in which plesiosaurs were often classified during the 19th century, along with the Pliosauridae and the Plesiosauridae. However, most of these traits led to many genera since recognized as belonging to other plesiosaur families being classified as elasmosaurids. Another family historically considered as distinct, the Cimoliasauridae, has since 2009 been recognized as a junior synonym of the Elasmosauridae. Along ...
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Basal (phylogenetics)
In phylogenetics, basal is the direction of the ''base'' (or root) of a phylogenetic tree#Rooted tree, rooted phylogenetic tree or cladogram. The term may be more strictly applied only to nodes adjacent to the root, or more loosely applied to nodes regarded as being close to the root. Note that extant taxa that lie on branches connecting directly to the root are not more closely related to the root than any other extant taxa. While there must always be two or more equally "basal" clades sprouting from the root of every cladogram, those clades may differ widely in taxonomic rank, Phylogenetic diversity, species diversity, or both. If ''C'' is a basal clade within ''D'' that has the lowest rank of all basal clades within ''D'', ''C'' may be described as ''the'' basal taxon of that rank within ''D''. The concept of a 'key innovation' implies some degree of correlation between evolutionary innovation and cladogenesis, diversification. However, such a correlation does not make a given ca ...
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Specific Name (zoology)
In zoological nomenclature, the specific name (also specific epithet, species epithet, or epitheton) is the second part (the second name) within the scientific name of a species (a binomen). The first part of the name of a species is the name of the genus or the generic name. The rules and regulations governing the giving of a new species name are explained in the article species description. For example, the scientific name for humans is ''Homo sapiens'', which is the species name, consisting of two names: ''Homo'' is the " generic name" (the name of the genus) and ''sapiens'' is the "specific name". Etymology Historically, ''specific name'' referred to the combination of what are now called the generic and specific names. Carl Linnaeus, who formalized binomial nomenclature, made explicit distinctions between specific, generic, and trivial names. The generic name was that of the genus, the first in the binomial, the trivial name was the second name in the binomial, and the ...
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Greek Language
Greek (, ; , ) is an Indo-European languages, Indo-European language, constituting an independent Hellenic languages, Hellenic branch within the Indo-European language family. It is native to Greece, Cyprus, Italy (in Calabria and Salento), southern Albania, and other regions of the Balkans, Caucasus, the Black Sea coast, Asia Minor, and the Eastern Mediterranean. It has the list of languages by first written accounts, longest documented history of any Indo-European language, spanning at least 3,400 years of written records. Its writing system is the Greek alphabet, which has been used for approximately 2,800 years; previously, Greek was recorded in writing systems such as Linear B and the Cypriot syllabary. The Greek language holds a very important place in the history of the Western world. Beginning with the epics of Homer, ancient Greek literature includes many works of lasting importance in the European canon. Greek is also the language in which many of the foundational texts ...
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Genus
Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In binomial nomenclature, the genus name forms the first part of the binomial species name for each species within the genus. :E.g. ''Panthera leo'' (lion) and ''Panthera onca'' (jaguar) are two species within the genus ''Panthera''. ''Panthera'' is a genus within the family Felidae. The composition of a genus is determined by taxonomy (biology), taxonomists. The standards for genus classification are not strictly codified, so different authorities often produce different classifications for genera. There are some general practices used, however, including the idea that a newly defined genus should fulfill these three criteria to be descriptively useful: # monophyly – all descendants of an ancestral taxon are grouped together (i.e. Phylogeneti ...
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Species Description
A species description is a formal scientific description of a newly encountered species, typically articulated through a scientific publication. Its purpose is to provide a clear description of a new species of organism and explain how it differs from species that have been previously described or related species. For a species to be considered valid, a species description must follow established guidelines and naming conventions dictated by relevant nomenclature codes. These include the International Code of Zoological Nomenclature (ICZN) for animals, the International Code of Nomenclature for algae, fungi, and plants (ICN) for plants, and the International Committee on Taxonomy of Viruses (ICTV) for viruses. A species description often includes photographs or other illustrations of type material and information regarding where this material is deposited. The publication in which the species is described gives the new species a formal scientific name. Some 1.9 million ...
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Gastroliths
A gastrolith, also called a stomach stone or gizzard stone, is a rock held inside a gastrointestinal tract. Gastroliths in some species are retained in the muscular gizzard and used to grind food in animals lacking suitable grinding teeth. In other species the rocks are ingested and pass through the digestive system and are frequently replaced. The grain size depends upon the size of the animal and the gastrolith's role in digestion. Other species use gastroliths as ballast.Rondeau, et aLarval Anurans Adjust Buoyancy in Response to Substrate IngestionCopeia: February 2005, Vol. 2005, No. 1, pp. 188–195. Particles ranging in size from sand to cobble have been documented. Etymology Gastrolith comes from the Ancient Greek γαστήρ (''gastēr''), meaning "stomach", and λίθος (''lithos''), meaning "stone". Occurrence Among living vertebrates, gastroliths are common among crocodiles, alligators, herbivorous birds, seals and sea lions. Domestic fowl require access to ''grit ...
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Gastralia
Gastralia (: gastralium) are dermal bones found in the ventral body wall of modern crocodilians and tuatara, and many prehistoric tetrapods. They are found between the sternum and pelvis, and do not articulate with the vertebrae. In these reptiles, gastralia provide support for the abdomen and attachment sites for abdominal muscles. The possession of gastralia may be ancestral for Tetrapoda and were possibly derived from the ventral scales found in animals like rhipidistians, labyrinthodonts, and ''Acanthostega'', and may be related to ventral elements of turtle plastrons. Similar, but not homologous cartilagenous elements, are found in the ventral body walls of lizards and anurans. These structures have been referred to as inscriptional ribs, based on their alleged association with the inscriptiones tendinae (the tendons that form the six pack in humans). However, the terminology for these gastral-like structures remains confused. Both types, along with sternal ribs (ossified ...
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Ribs
The rib cage or thoracic cage is an endoskeletal enclosure in the thorax of most vertebrates that comprises the ribs, vertebral column and sternum, which protect the vital organs of the thoracic cavity, such as the heart, lungs and great vessels and support the shoulder girdle to form the core (anatomy), core part of the axial skeleton. A typical human skeleton, human thoracic cage consists of 12 pairs of ribs and the adjoining costal cartilages, the sternum (along with the manubrium and xiphoid process), and the 12 thoracic vertebrae articulating with the ribs. The thoracic cage also provides attachments for extrinsic skeletal muscles of the neck, upper limbs, upper abdomen and back, and together with the overlying skin and associated fascia and muscles, makes up the thoracic wall. In tetrapods, the rib cage intrinsically holds the muscles of respiration (thoracic diaphragm, diaphragm, intercostal muscles, etc.) that are crucial for active inhalation and forced exhalation, and ...
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