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Gastrolith
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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plesiosaurs
The Plesiosauria or plesiosaurs are an Order (biology), order or clade of extinct Mesozoic marine reptiles, belonging to the Sauropterygia. Plesiosaurs first appeared in the latest Triassic Period (geology), Period, possibly in the Rhaetian stage, about 203 million years ago. They became especially common during the Jurassic Period, thriving until their disappearance due to the Cretaceous–Paleogene extinction event at the end of the Cretaceous Period, about 66 million years ago. They had a worldwide oceanic distribution, and some species at least partly inhabited freshwater environments. Plesiosaurs were among the first fossil reptiles discovered. In the beginning of the nineteenth century, scientists realised how distinctive their build was and they were named as a separate order in 1835. The first plesiosaurian genus, the eponymous ''Plesiosaurus'', was named in 1821. Since then, more than a hundred valid species have been described. In the early twenty-first cent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Elasmosaurid Plesiosaurs
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 with ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Caudipteryx
''Caudipteryx'' (meaning "tail feather") is a genus of small oviraptorosaur dinosaurs that lived in Asia during the Early Cretaceous, around 124.6 million years ago. They were feathered and extremely birdlike in their overall appearance, to the point that some paleontologists suggested it was a bird. Two species have been described: ''C. zoui'' (the type species), in 1998, and ''C. dongi'', in 2000. It had a stout trunk, long legs and was probably a swift runner. The discovery of ''Caudipteryx'' has led to many intensive studies and debate over the relationship of birds and dinosaurs. History In 1997, several well-preserved dinosaur skeletons were recovered from the Jiulongsong Member of the Chaomidianzi Formation (now Jianshangou Bed of the Yixian Formation), at the Sihetun locality of Liaoning province, China. The fossils were later described in 1998 and used as the type specimens for the new dinosaur taxa ''Caudipteryx'' and '' Protarchaeopteryx''. ''Caudipteryx'' was ere ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gizzard
The gizzard, also referred to as the ventriculus, gastric mill, and gigerium, is an organ found in the digestive tract of some animals, including archosaurs (birds and other dinosaurs, crocodiles, alligators, pterosaurs), earthworms, some gastropods, some fish, and some crustaceans. This specialized stomach constructed of thick muscular walls is used for grinding up food, often aided by particles of stone or grit. In certain insects and molluscs, the gizzard features chitinous plates or teeth. Etymology The word ''gizzard'' comes from the Middle English ''giser'', which derives from a similar word in Old French ''gésier'', which itself evolved from the Latin">-4; we might wonder whether there's a point at which it's appropriate to talk of the beginnings of French, that is, when it wa ... ''gésier'', which itself evolved from the Latin ''gigeria'', meaning giblets. Structure In birds Birds swallow food and store it in their crop if necessary. Then the food passes into thei ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dinosaurs
Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic Geological period, period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the #Evolutionary history, evolution of dinosaurs is a subject of active research. They became the dominant terrestrial vertebrates after the Triassic–Jurassic extinction event 201.3 mya and their dominance continued throughout the Jurassic and Cretaceous periods. The fossil record shows that birds are feathered dinosaurs, Evolution of birds, having evolved from earlier Theropoda, theropods during the Late Jurassic epoch, and are the only dinosaur lineage known to have survived the Cretaceous–Paleogene extinction event approximately 66 mya. Dinosaurs can therefore be divided into avian dinosaurs—birds—and the extinct non-avian dinosaurs, which are all dinosaurs other than birds. Dinosaurs are varied from taxonomy (biology), taxonomic, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alligator
An alligator, or colloquially gator, is a large reptile in the genus ''Alligator'' of the Family (biology), family Alligatoridae in the Order (biology), order Crocodilia. The two Extant taxon, extant species are the American alligator (''A. mississippiensis'') and the Chinese alligator (''A. sinensis''). Additionally, several extinct species of alligator are known from fossil remains. Alligators first appeared during the late Eocene epoch about 37 million years ago. The term "alligator" is likely an Anglicisation (linguistics), anglicized form of ', Spanish language, Spanish for "the lizard", which early Spanish explorers and settlers in Florida called the alligator. Early English language, English spellings of the name included ''allagarta'' and ''alagarto''. Evolution Alligators and caimans split in North America during the early Tertiary period, Tertiary or late Cretaceous (about 53 million to 65 million years ago). The Chinese alligator split from the America ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crocodile
Crocodiles (family (biology), family Crocodylidae) or true crocodiles are large, semiaquatic reptiles that live throughout the tropics in Africa, Asia, the Americas and Australia. The term "crocodile" is sometimes used more loosely to include all extant taxon, extant members of the order (biology), order Crocodilia, which includes the alligators and caimans (both members of the family Alligatoridae), the gharial and false gharial (both members of the family Gavialidae) as well as other extinct Taxon, taxa. Crocodile Measurement, size, Morphology (biology), morphology, behaviour and ecology differ among species. However, they have many similarities in these areas as well. All crocodiles are semiaquatic and tend to congregate in freshwater habitats such as rivers, lakes, wetlands and sometimes in brackish water and Seawater, saltwater. They are carnivorous animals, feeding mostly on vertebrates such as fish, reptiles, birds and mammals, and sometimes on invertebrates such as mol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
George Reber Weiland
George may refer to: Names * George (given name) * George (surname) People * George (singer), American-Canadian singer George Nozuka, known by the mononym George * George Papagheorghe, also known as Jorge / GEØRGE * George, stage name of Giorgio Moroder * George, son of Andrew I of Hungary Places South Africa * George, South Africa, a city ** George Airport United States * George, Iowa, a city * George, Missouri, a ghost town * George, Washington, a city * George County, Mississippi * George Air Force Base, a former U.S. Air Force base located in California Computing * George (algebraic compiler) also known as 'Laning and Zierler system', an algebraic compiler by Laning and Zierler in 1952 * GEORGE (computer), early computer built by Argonne National Laboratory in 1957 * GEORGE (operating system), a range of operating systems (George 1–4) for the ICT 1900 range of computers in the 1960s * GEORGE (programming language), an autocode system invented by Charles Leonard Hamblin ... [...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''. Though the fossil record is incomplete, numerous studies have demonstrated that there is enough information available to give a good understanding of the pattern of diversification of life on Earth. In addition, the record can predict and fill gaps such as the discovery of '' Tiktaalik'' in the arctic of Canada. Paleontology includes the study of fossils: their age, method of formation, and evolutionary significance. Specimens are sometimes considered to be fossils if they are over 10,000 years old. The oldest fossils are around 3.48 billion years to 4.1 billion years old. Early edition, published online before prin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
