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San Gregorio Formation, Venezuela
The San Gregorio Formation is a lithostratigraphic unit dating back to the Pliocene to Pleistocene of Venezuela. The formation is split into three members, the older Vergel Member (Late Pliocene to earliest Pleistocene), the Cocuiza Member (Pleistocene) and the Río Seco Member. During this time the region is thought to have been covered by a mixed environment of open grassland and forested areas surrounding a permanent freshwater system. The diverse fauna of the San Gregorio Formation, including a variety of freshwater fish, crocodilians, turtles and snakes, also includes many mammals interpreted to have been part of the first major wave of the Great American Interchange in addition to native clades such as glyptodonts, ground sloths and caviomorph rodents. Stratigraphy The San Gregorio Formation overlies the Codore Formation and forms the most recent sequence of the stratigraphic section. Outcrops of this formation are found in Falcón State, northeast of the town of Urumaco. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zanclean
The Zanclean is the lowest stage or earliest age on the geologic time scale of the Pliocene. It spans the time between 5.332 ± 0.005 Ma (million years ago) and 3.6 ± 0.005 Ma. It is preceded by the Messinian Age of the Miocene Epoch, and followed by the Piacenzian Age. The Zanclean can be correlated with regionally used stages, such as the Opoitian of New Zealand, and the Tabianian or Dacian of Central Europe. It also corresponds to the late Hemphillian to mid-Blancan North American Land Mammal Ages. In California, the Zanclean roughly corresponds to the middle part of the Delmontian stage. Definition The Zanclean Stage was introduced by Giuseppe Seguenza in 1868. It is named after ''Zancle'', the pre-Roman name for the Italian city of Messina on Sicily. The base of the Zanclean (and the Pliocene Series) lies with the top of magnetic chronozone Cr3 (about 100,000 years before the Thvera normal subchronozone C3n.4n). The base is also close to the extinction level of the calc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Caviomorpha
Caviomorpha is the rodent infraorder or parvorder that unites all New World hystricognaths. It is supported by both fossil and molecular evidence. The Caviomorpha was for a time considered to be a separate order outside the Rodentia, but is now accepted as a genuine part of the rodents. Caviomorphs include the extinct Heptaxodontidae (giant hutias) and extant families of chinchilla rats, hutias, guinea pigs and the capybara, chinchillas and viscachas, tuco-tucos, agoutis, pacas, pacaranas, spiny rats, New World porcupines, coypu and octodonts (Vassallo and Antenucci, 2015). Origin The first known rodent fossils in South America are represented by the three taxa ''Cachiyacuy contamanensis'', ''C. kummeli'', and ''Canaanimys maquiensis'', as well as teeth from ''Eobranisamys'' sp. (Dasyproctidae) and ''Eospina'' sp., the latter two found also in the Santa Rosa fauna from the late Eocene or early Oligocene. By the late Oligocene, all superfamilies and most families of caviomor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mata Mata
Matamata () is a town in Waikato, New Zealand. It is located near the base of the Kaimai Ranges, and is a thriving farming area known for Thoroughbred horse breeding and training pursuits. It is part of the Matamata-Piako District, which takes in the surrounding rural areas, as well as Morrinsville and Te Aroha. State Highway 27 and the Kinleith Branch railway run through the town. The town has a population of as of A nearby farm was the location for the Hobbiton Movie Set in Peter Jackson's ''The Lord of the Rings''. The New Zealand government decided to leave the Hobbit holes built on location as tourist attractions. During the period between the filming of '' The Lord of the Rings: The Return of the King'' and '' The Hobbit: An Unexpected Journey'' they had no furniture or props, but could be entered with vistas of the farm viewed from inside them. A "Welcome to Hobbiton" sign has been placed on the main road. In 2011, parts of Hobbiton began to close in preparation for th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crocodylus Falconensis
''Crocodylus falconensis'' is an extinct species of crocodile known from the early Pliocene of the lower part of the Vergel Member of the San Gregorio Formation of Venezuela. ''C. falconensis'' was named in 2013 after Falcón State and is thought to be the basalmost species of '' Crocodylus'' found in the Neotropics. Description ''C. falconensis'' was a medium-sized species of crocodile with a robust, generalist skull shape. The orbits and the supratemporal fenestrae are notably smaller than those of other ''Crocodylus'' species of the same age, while the nares are comparably larger (however still small relative to the overall skull size). The premaxilla surrounds the nares entirely, excluding the nasal bones from contacting them. Another feature differentiation ''Crocodylus falconensis'' from other species of the genus is that the supraoccipital reaches or at least almost reaches the foramen magnum. The roughly triangular skull had a prominent notch located behind the nares to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Foraminifera
Foraminifera (; Latin for "hole bearers"; informally called "forams") are single-celled organisms, members of a phylum or class of amoeboid protists characterized by streaming granular Ectoplasm (cell biology), ectoplasm for catching food and other uses; and commonly an external shell (called a "Test (biology), test") of diverse forms and materials. Tests of chitin (found in some simple genera, and Textularia in particular) are believed to be the most primitive type. Most foraminifera are marine, the majority of which live on or within the seafloor sediment (i.e., are benthos, benthic), while a smaller number float in the water column at various depths (i.e., are planktonic), which belong to the suborder Globigerinina. Fewer are known from freshwater or brackish conditions, and some very few (nonaquatic) soil species have been identified through molecular analysis of small subunit ribosomal DNA. Foraminifera typically produce a test (biology), test, or shell, which can have eithe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sciades
''Sciades'' is a genus of sea catfishes mostly found along the Atlantic Ocean and Caribbean Sea coasts of Central and South America. One species, ''S. dowii'', occurs on the Pacific side from Panama to Ecuador, another, ''S. paucus'', is a freshwater form found in Australia, while ''S. sona'' is a widespread species found along the Indian Ocean coasts of South Asia east into the Pacific to Polynesia. The genus '' Ariopsis'' has been merged with ''Sciades'' by some authorities. Currently, eight described species are in this genus: * '' Sciades couma'' (Valenciennes, 1840) (Couma sea-catfish) * '' Sciades dowii'' ( T. N. Gill, 1863) (brown sea-catfish) * '' Sciades herzbergii'' (Bloch, 1794) (Pemecou sea catfish) * '' Sciades parkeri'' ( Traill, 1832) (gillbacker sea catfish) * '' Sciades passany'' (Valenciennes, 1840) (Passany sea catfish) * '' Sciades paucus'' ( Kailola, 2000) * '' Sciades proops'' (Valenciennes Valenciennes (, also , , ; nl, label=also Dutch, Valencijn; pcd ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Potamotrygon
''Potamotrygon'' is a genus of freshwater stingrays in the family Potamotrygonidae native to the rivers of South America, and sometimes seen in the aquarium trade. Like other stingrays, the fishes of this genus have venomous barbs at the base of their tails, and their stings are dangerous to humans. It is said that the natives of South America fear the stingray more than they do fear the piranha. ''Potamotrygon'' vary considerably in color, pattern and size, with the maximum disc width ranging from in ''P. wallacei'' to in ''P. brachyura''. In the aquarium Though freshwater stingray of other genera do appear in the trade, most are from ''Potamotrygon''. They are best kept with a deep, sandy substrate, in which they bury themselves, often with only the eyes visible. They are not territorial with other animals and can be kept in groups, provided a large enough aquarium is provided. They are carnivorous bottom feeders and require strong filtration as they are rather sensitive t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rubidium–strontium Dating
The rubidium-strontium dating method is a radiometric dating technique, used by scientists to determine the age of rocks and minerals from their content of specific isotopes of rubidium (87Rb) and strontium (87Sr, 86Sr). One of the two naturally occurring isotopes of rubidium, 87Rb, decays to 87Sr with a half-life of 49.23 billion years. The radiogenic daughter, 87Sr, produced in this decay process is the only one of the four naturally occurring strontium isotopes that was not produced exclusively by stellar nucleosynthesis predating the formation of the Solar System. Over time, decay of 87Rb increases the amount of radiogenic 87Sr while the amount of other Sr isotopes remains unchanged. The ratio 87Sr/86Sr in a mineral sample can be accurately measured using a mass spectrometer. If the amount of Sr and Rb isotopes in the sample when it formed can be determined, the age can be calculated from the increase in 87Sr/86Sr. Different minerals that crystallized from the same silicic melt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Limestone
Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms when these minerals precipitate out of water containing dissolved calcium. This can take place through both biological and nonbiological processes, though biological processes, such as the accumulation of corals and shells in the sea, have likely been more important for the last 540 million years. Limestone often contains fossils which provide scientists with information on ancient environments and on the evolution of life. About 20% to 25% of sedimentary rock is carbonate rock, and most of this is limestone. The remaining carbonate rock is mostly dolomite, a closely related rock, which contains a high percentage of the mineral dolomite, . ''Magnesian limestone'' is an obsolete and poorly-defined term used variously for dolomite, for limes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sandstone
Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates) because they are the most resistant minerals to weathering processes at the Earth's surface. Like uncemented sand, sandstone may be any color due to impurities within the minerals, but the most common colors are tan, brown, yellow, red, grey, pink, white, and black. Since sandstone beds often form highly visible cliffs and other topographic features, certain colors of sandstone have been strongly identified with certain regions. Rock formations that are primarily composed of sandstone usually allow the percolation of water and other fluids and are porous enough to store large quantities, making them valuable aquifers and petroleum reservoirs. Quartz-bearing sandstone can be changed into quartzite through metamorphism, usually related to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Robert Masterman Stainforth
R. M. Stainforth (known usually as Charles) (October 5 1915 – September 30 2002) was a micropaleontologist and stratigrapher best known for his innovative work on the application of planktonic foraminifera to worldwide stratigraphic correlation. His work was based on the microfauna and stratigraphy of South America, especially as related to petroleum geology. Born in Kingston-upon-Hull in the East Riding of Yorkshire, Stainforth studied at the Royal School of Mines in London, where he earned a ‘Bachelor of Science in the Technology of Oil’ in 1938. Upon graduation he was offered a position as a paleontologist at Pointe-à-Pierre in Trinidad working for Trinidad Leaseholds Ltd. Those working at the laboratory, including Stainforth, had a great influence on the study of stratigraphy in the years that followed. The management of the company, encouraged by Dr. Hans Kugler and a succession of Chief Geologists, allowed a generous publication policy, not always the case in industry ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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