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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 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''. Stone ... [...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 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''. Stones ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plesiosaurs
The Plesiosauria (; Greek: πλησίος, ''plesios'', meaning "near to" and ''sauros'', meaning "lizard") or plesiosaurs are an order or clade of extinct Mesozoic marine reptiles, belonging to the Sauropterygia. Plesiosaurs first appeared in the latest Triassic 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Caudipteryx
''Caudipteryx'' (which means "tail feather") is a genus of peacock-sized theropod dinosaurs that lived in the Barremian age of the early Cretaceous (about 124.6 million years ago). They were feathered and extremely birdlike in their overall appearance, to the point that some paleontologists think it was a bird. Two species have been described: ''C. zoui'' (the type species), in 1998, and ''C. dongi'', in 2000. ''Caudipteryx'' fossils were first discovered in the Yixian Formation of the Sihetun area of Liaoning Province, northeastern China in 1997. Description ''Caudipteryx'', like many other maniraptorans, has a mix of reptile- and bird-like anatomical features.Witmer, L.M. (2005). “The Debate on Avian Ancestry; Phylogeny, Function and Fossils”, ''Mesozoic Birds: Above the Heads of Dinosaurs'' : 3–30. It had a short, boxy skull with a beak-like snout that retained only a few tapered teeth in the front of the upper jaw. It had a stout trunk, long legs and was proba ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alligator
An alligator is a large reptile in the Crocodilia order in the genus ''Alligator'' of the family Alligatoridae. 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 Oligocene epoch about 37 million years ago. The name "alligator" is probably an anglicization, anglicized form of ', the Spanish term for "the lizard", which early Spanish explorers and settlers in Florida called the alligator. Later English spellings of the name included ''allagarta'' and ''alagarto''. Evolution Alligators and caimans split in North America during the early Tertiary or late Cretaceous (about 53 million to about 65 million years ago). The Chinese alligator split from the American alligator about 33 million years ago and probably descended from a lineage that crossed Beringia, the Bering land bri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sea Lion
Sea lions are pinnipeds characterized by external ear flaps, long foreflippers, the ability to walk on all fours, short and thick hair, and a big chest and belly. Together with the fur seals, they make up the family Otariidae, eared seals. The sea lions have six extant and one extinct species (the Japanese sea lion) in five genera. Their range extends from the subarctic to tropical waters of the global ocean in both the Northern and Southern Hemispheres, with the notable exception of the northern Atlantic Ocean. They have an average lifespan of 20–30 years. A male California sea lion weighs on average about and is about long, while the female sea lion weighs and is long. The largest sea lions are Steller's sea lions, which can weigh and grow to a length of . Sea lions consume large quantities of food at a time and are known to eat about 5–8% of their body weight (about ) at a single feeding. Sea lions can move around in water and at their fastest they can r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hadrosaur Hadrosaurids (), or duck-billed dinosaurs, are members of the ornithischian family Hadrosauridae. This group is known as the duck-billed dinosaurs for the flat duck-bill appearance of the bones in their snouts. The ornithopod family, which includes genera such as ''Edmontosaurus'' and ''Parasaurolophus'', was a common group of herbivores during the Late Cretaceous Period. Hadrosaurids are descendants of the Upper Jurassic/Lower Cretaceous iguanodontian dinosaurs and had a similar body layout. Hadrosaurs were among the most dominant herbivores during the Late Cretaceous in Asia and North America, and during the close of the Cretaceous several lineages dispersed into Europe, Africa, South America and Antarctica. Li |
