Edgarosaurus Muddi
''Edgarosaurus'' is a genus of polycotylid plesiosaur from the Thermopolis Shale, containing one species, ''E. muddi''.Druckenmiller, PS, 2002. "Osteology of a new plesiosaur from the lower Cretaceous (Albian) Thermopolis Shale of Montana". ''Journal of Vertebrate Paleontology'' 22: 29-42. (Abstract) The type specimen was found in Early Cretaceous (late Albian) rocks in the state of Montana in the United States. At the time, this location was covered by part of the Western Interior Seaway. ''Edgarosaurus'' was one of the first polycotylids that evolved to become native to the Western Interior Seaway. The holotype (which is currently the only known specimen) consists of the skull, neck, parts of the spine and the left front flipper. History of study The well-preserved holotype specimen of ''Edgarosaurus'' (MOR 751) was found in the Shell Creek Member, the uppermost of the three members of the Thermopolis Shale, during the spring of 1993. The specimen's skull is complete and was ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Early Cretaceous
The Early Cretaceous (geochronological name) or the Lower Cretaceous ( chronostratigraphic name), is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 145 Ma to 100.5 Ma. Geology Proposals for the exact age of the Barremian-Aptian boundary ranged from 126 to 117 Ma until recently (as of 2019), but based on drillholes in Svalbard the defining early Aptian Oceanic Anoxic Event 1a (OAE1a) was carbon isotope dated to 123.1±0.3 Ma, limiting the possible range for the boundary to c. 122–121 Ma. There is a possible link between this anoxic event and a series of Early Cretaceous large igneous provinces (LIP). The Ontong Java- Manihiki- Hikurangi large igneous province, emplaced in the South Pacific at c. 120 Ma, is by far the largest LIP in Earth's history. The Ontong Java Plateau today covers an area of 1,860,000 km2. In the Indian Ocean another LIP began to form at c. 120 Ma, the Kergue ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Species (biology)
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. Other ways of defining species include their karyotype, DNA sequence, morphology, behaviour or ecological niche. In addition, paleontologists use the concept of the chronospecies since fossil reproduction cannot be examined. The most recent rigorous estimate for the total number of species of eukaryotes is between 8 and 8.7 million. However, only about 14% of these had been described by 2011. All species (except viruses) are given a two-part name, a "binomial". The first part of a binomial is the genus to which the species belongs. The second part is called the specific name or the specific epithet (in botanical nomenclature, also sometimes in zoologi ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Polycotylids
Polycotylidae is a family of plesiosaurs from the Cretaceous, a sister group to Leptocleididae. Polycotylids first appeared during the Albian stage of the Early Cretaceous, before becoming abundant and widespread during the early Late Cretaceous. Several species survived into the final stage of the Cretaceous, the Maastrichtian. With their short necks and large elongated heads, they resemble the pliosaurs, but closer phylogenetic studies indicate that they share many common features with the Leptocleididae and Elasmosauridae. They have been found worldwide, with specimens reported from New Zealand, Australia, Japan, Morocco, the US, Canada, Eastern Europe, and South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe .... Phylogeny Cladogram after Albright, Gillette and ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Early Cretaceous Plesiosaurs Of North America
{{disambiguation, geo ...
Early may refer to: History * The beginning or oldest part of a defined historical period, as opposed to middle or late periods, e.g.: ** Early Christianity ** Early modern Europe Places in the United States * Early, Iowa * Early, Texas * Early Branch, a stream in Missouri * Early County, Georgia Other uses * ''Early'' (Scritti Politti album), 2005 * ''Early'' (A Certain Ratio album), 2002 * Early (name) * Early effect, an effect in transistor physics * Early Records, a record label * the early part of the morning See also * Earley (other) Earley is a town in England. Earley may also refer to: * Earley (surname), a list of people with the surname Earley * Earley (given name), a variant of the given name Earlene * Earley Lake, a lake in Minnesota *Earley parser, an algorithm *Earley ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Timeline Of Plesiosaur Research
This timeline of plesiosaur research is a chronologically ordered list of important fossil discoveries, controversies of interpretation, taxonomic revisions, and cultural portrayals of plesiosaurs, an order of marine reptiles that flourished during the Mesozoic Era. The first scientifically documented plesiosaur fossils were discovered during the early 19th century by Mary Anning. Plesiosaurs were actually discovered and described before dinosaurs. They were also among the first animals to be featured in artistic reconstructions of the ancient world, and therefore among the earliest prehistoric creatures to attract the attention of the lay public. Plesiosaurs were originally thought to be a kind of primitive transitional form between marine life and terrestrial reptiles. However, now plesiosaurs are recognized as highly derived marine reptiles descended from terrestrial ancestors. Early researchers thought that plesiosaurs laid eggs like most reptiles. They commonly imagined p ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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List Of Plesiosaur Genera
This list of plesiosaurs is a comprehensive listing of all genera that have ever been included in the order Plesiosauria, excluding purely vernacular terms. The list includes all commonly accepted genera, but also genera that are now considered invalid, doubtful (''nomen dubium''), or were not formally published (''nomen nudum''), as well as junior synonyms of more established names, and genera that are no longer considered plesiosaurs. The list currently includes 201 genera. Scope and terminology There is no official, canonical list of plesiosaur genera but one of the most thorough attempts can be found on the Plesiosauria section of Mikko Haaramo's Phylogeny Archive; also pertinent is the Plesiosaur Genera section at Adam Stuart Smith's Plesiosaur Directory.See Smith, ''Plesiosaur Genera''. Naming conventions and terminology follow the International Code of Zoological Nomenclature. Technical terms used include: * Junior synonym: A name which describes the same taxon as a previou ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Polycotylid
Polycotylidae is a family of plesiosaurs from the Cretaceous, a sister group to Leptocleididae. Polycotylids first appeared during the Albian stage of the Early Cretaceous, before becoming abundant and widespread during the early Late Cretaceous. Several species survived into the final stage of the Cretaceous, the Maastrichtian. With their short necks and large elongated heads, they resemble the pliosaurs, but closer phylogenetic studies indicate that they share many common features with the Leptocleididae and Elasmosauridae. They have been found worldwide, with specimens reported from New Zealand, Australia, Japan, Morocco, the US, Canada, Eastern Europe, and South America. Phylogeny Cladogram A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to ... after Albright, Gillette and ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Mandible
In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower teeth in place. The mandible sits beneath the maxilla. It is the only movable bone of the skull (discounting the ossicles of the middle ear). It is connected to the temporal bones by the temporomandibular joints. The bone is formed in the fetus from a fusion of the left and right mandibular prominences, and the point where these sides join, the mandibular symphysis, is still visible as a faint ridge in the midline. Like other symphyses in the body, this is a midline articulation where the bones are joined by fibrocartilage, but this articulation fuses together in early childhood.Illustrated Anatomy of the Head and Neck, Fehrenbach and Herring, Elsevier, 2012, p. 59 The word "mandible" derives from the Latin word ''mandibula'', "jawbone" (literally "one used for chewing"), from '' mandere'' "to chew" and ''-bula'' ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Braincase
In human anatomy, the neurocranium, also known as the braincase, brainpan, or brain-pan is the upper and back part of the skull, which forms a protective case around the brain. In the human skull, the neurocranium includes the calvaria or skullcap. The remainder of the skull is the facial skeleton. In comparative anatomy, neurocranium is sometimes used synonymously with endocranium or chondrocranium. Structure The neurocranium is divided into two portions: * the membranous part, consisting of flat bones, which surround the brain; and * the cartilaginous part, or chondrocranium, which forms bones of the base of the skull. In humans, the neurocranium is usually considered to include the following eight bones: * 1 ethmoid bone * 1 frontal bone * 1 occipital bone * 2 parietal bones * 1 sphenoid bone * 2 temporal bones The ossicles (three on each side) are usually not included as bones of the neurocranium. There may variably also be extra sutural bones present. Below the ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Pineal Foramen
A parietal eye, also known as a third eye or pineal eye, is a part of the epithalamus present in some vertebrates. The eye is located at the top of the head, is photoreceptive and is associated with the pineal gland, regulating circadian rhythmicity and hormone production for thermoregulation. The hole in the head which contains the eye is known as a pineal foramen or parietal foramen, since it is often enclosed by the parietal bones. Presence in various animals The parietal eye is found in the tuatara, most lizards, frogs, salamanders, certain bony fish, sharks, and lampreys. It is absent in mammals, but was present in their closest extinct relatives, the therapsids, suggesting it was lost during the course of the mammalian evolution due to it being useless in endothermic animals. It is also absent in the ancestrally endothermic ("warm-blooded") archosaurs such as birds. The parietal eye is also lost in ectothermic ("cold-blooded") archosaurs like crocodilians, and in turtle ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Premaxilla
The premaxilla (or praemaxilla) is one of a pair of small cranial bones at the very tip of the upper jaw of many animals, usually, but not always, bearing teeth. In humans, they are fused with the maxilla. The "premaxilla" of therian mammal has been usually termed as the incisive bone. Other terms used for this structure include premaxillary bone or ''os premaxillare'', intermaxillary bone or ''os intermaxillare'', and Goethe's bone. Human anatomy In human anatomy, the premaxilla is referred to as the incisive bone (') and is the part of the maxilla which bears the incisor teeth, and encompasses the anterior nasal spine and alar region. In the nasal cavity, the premaxillary element projects higher than the maxillary element behind. The palatal portion of the premaxilla is a bony plate with a generally transverse orientation. The incisive foramen is bound anteriorly and laterally by the premaxilla and posteriorly by the palatine process of the maxilla. It is formed from ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |
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Peloneustes
''Peloneustes'' (meaning "mud swimmer") is a genus of pliosaurid plesiosaur from the Middle Jurassic of England. Its remains are known from the Peterborough Member of the Oxford Clay Formation, which is Callovian in age. It was originally described as a species of ''Plesiosaurus'' by palaeontologist Harry Govier Seeley in 1896, before being given its own genus by naturalist Richard Lydekker in 1889. While many species have been assigned to ''Peloneustes'', ''P. philarchus'' is currently the only one still considered valid, with the others moved to different genera, considered '' nomina dubia'', or synonymised with ''P. philarchus''. Some of the material formerly assigned to ''P. evansi'' have since been reassigned to ''" Pliosaurus" andrewsi''. ''Peloneustes'' is known from many specimens, including some very complete material. With a total length of , ''Peloneustes'' is not a large pliosaurid. It had a large, triangular skull, which occupied about a fifth of its body lengt ... [...More Info...]       [...Related Items...]     OR:     [Wikipedia]   [Google]   [Baidu]   |