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Yerrapalli Formation
The Yerrapalli Formation is a Triassic rock formation consisting primarily of mudstones that outcrops in the Pranhita–Godavari Basin in southeastern India. The Yerrapalli Formation preserves fossils of freshwater and terrestrial vertebrates as well as trace fossils of invertebrates.Yerrapalli Formation at Fossilworks.org The fauna includes amphibians, |
Geological Formation
A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics ( lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exposed in a geographical region (the stratigraphic column). It is the fundamental unit of lithostratigraphy, the study of strata or rock layers. A formation must be large enough that it can be mapped at the surface or traced in the subsurface. Formations are otherwise not defined by the thickness of their rock strata, which can vary widely. They are usually, but not universally, tabular in form. They may consist of a single lithology (rock type), or of alternating beds of two or more lithologies, or even a heterogeneous mixture of lithologies, so long as this distinguishes them from adjacent bodies of rock. The concept of a geologic formation goes back to the beginnings of modern scientific geology. The term was used by Abraham Gottlob Wer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Archosauromorph
Archosauromorpha (Greek for "ruling lizard forms") is a clade of diapsid reptiles containing all reptiles more closely related to archosaurs (such as crocodilians and dinosaurs, including birds) rather than lepidosaurs (such as tuataras, lizards, and snakes). Archosauromorphs first appeared during the late Middle Permian or Late Permian, though they became much more common and diverse during the Triassic period. Although Archosauromorpha was first named in 1946, its membership did not become well-established until the 1980s. Currently Archosauromorpha encompasses four main groups of reptiles: the stocky, herbivorous allokotosaurs and rhynchosaurs, the hugely diverse Archosauriformes, and a polyphyletic grouping of various long-necked reptiles including ''Protorosaurus'', tanystropheids, and ''Prolacerta''. Other groups including pantestudines (turtles and their extinct relatives) and the semiaquatic choristoderes have also been placed in Archosauromorpha by some authors. A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kannemeyeriiform
Kannemeyeriiformes is a group of large-bodied Triassic dicynodonts. As a clade, Kannemeyeriiformes has been defined to include the species ''Kannemeyeria simocephalus'' and all dicynodonts more closely related to it than to the species '' Lystrosaurus murrayi''. Evolutionary history Despite being the most species-rich group of dicynodonts in the Triassic Period, kannemeyeriiforms exhibit much less diversity in terms of their anatomy and ecological roles than the dicynodonts from the Permian Period. Lystrosauridae is thought to be the most closely related group (sister taxon) to Kannemeyeriiformes, and since the earliest lystrosaurids are known from the Late Permian, the divergence of these two groups must have occurred at least as far back as this time, implying that a long ghost lineage must exist. Although no kannemeyeriiforms have been found in the Late Permian yet, the recent discovery of ''Sungeodon'' helps fill a gap in the early fossil record of the group by showing that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rechnisaurus Cristarhynchus
''Rechnisaurus'' is an extinct genus of dicynodont from the Middle Triassic (Anisian) Yerrapalli Formation of India. It contains a single species, ''Rechnisaurus cristarhynchus''. History ''Rechnisaurus'' has had a long history of confusion with the far more widespread dicynodont ''Kannemeyeria''. ''Rechnisaurus cristarhynchus'' was originally described as a new genus and species in 1970, on the basis of fossils from India. Later in the 1970s, additional specimens were found in Africa (namely the Ntawere Formation of Zambia and the Omingonde Formation of Namibia) and referred to the species. These African fossils were noted to be very similar to ''Kannemeyeria'', so ''Rechnisaurus'' was renamed as a species of ''Kannemeyeria'', ''Kannemeyeria cristarhynchus''. However, in 1989 the original Indian fossils were re-compared to ''Kannemeyeria'' and found to be distinct, so ''Rechnisaurus'' was re-established in a more restricted sense including only the Indian fossils. The African ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gondwana
Gondwana () was a large landmass, often referred to as a supercontinent, that formed during the late Neoproterozoic (about 550 million years ago) and began to break up during the Jurassic period (about 180 million years ago). The final stages of break-up, involving the separation of Antarctica from South America (forming the Drake Passage) and Australia, occurred during the Paleogene. Gondwana was not considered a supercontinent by the earliest definition, since the landmasses of Baltica, Laurentia, and Siberia were separated from it. To differentiate it from the Indian region of the same name (see ), it is also commonly called Gondwanaland. Gondwana was formed by the accretion of several cratons. Eventually, Gondwana became the largest piece of continental crust of the Palaeozoic Era, covering an area of about , about one-fifth of the Earth's surface. During the Carboniferous Period, it merged with Laurasia to form a larger supercontinent called Pangaea. Gondwana (and Pan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ntawere Formation
The Ntawere Formation is a Middle Triassic (Anisian) geological formation in Zambia, preserving fossils of synapsids, archosaurs, and temnospondyls. Geology Several different facies are present in the Ntawere Formation, reconstructing a floodplain environment. The coarsest facies are trough cross-bedded conglomeratic sandstone full of mineral concretions. These coarse deposits formed in ancient channels such as riverbeds. Another type of facies involves thick beds of mudstone interbedding with thinner layers of fine-grained sandstone, indicating alternating low- and high-energy water flow within the channels. Graded sandstone to mudstone overbank deposits (complete with ripple marks) occur near channel deposits. Extensive successions of laminated or massive mudstone are common, often containing slickensides, calcareous nodules or layers (marls), and/or hematite nodules. These types of thick mud/marl layers likely formed in more quiet parts of the floodplain isolated from turbu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Member (geology)
A stratigraphic unit is a volume of rock of identifiable origin and relative age range that is defined by the distinctive and dominant, easily mapped and recognizable petrographic, lithologic or paleontologic features ( facies) that characterize it. Units must be ''mappable'' and ''distinct'' from one another, but the contact need not be particularly distinct. For instance, a unit may be defined by terms such as "when the sandstone component exceeds 75%". Lithostratigraphic units Sequences of sedimentary and volcanic rocks are subdivided the basis of their shared or associated lithology. Formally identified lithostratigraphic units are structured in a hierarchy of lithostratigraphic rank, higher rank units generally comprising two or more units of lower rank. Going from smaller to larger in rank, the main lithostratigraphic ranks are Bed, Member, Formation, Group and Supergroup. Formal names of lithostratigraphic units are assigned by geological surveys. Units of formation or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lithostratigraphy
Lithostratigraphy is a sub-discipline of stratigraphy, the geological science associated with the study of strata or rock layers. Major focuses include geochronology, comparative geology, and petrology. In general, strata are primarily igneous or sedimentary relating to how the rock was formed. Sedimentary layers are laid down by deposition of sediment associated with weathering processes, decaying organic matter (biogenic) or through chemical precipitation. These layers are often distinguishable as having many fossils and are important for the study of biostratigraphy. Igneous layers occur as stacks of lava flows, layers of lava fragments (called tephra) both erupted onto the Earth's surface by volcanoes, and in layered intrusions formed deep underground. Igneous layers are generally devoid of fossils and represent magmatic or volcanic activity that occurred during the geologic history of an area. There are a number of principles that are used to explain the appearance of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monsoonal
A monsoon () is traditionally a seasonal reversing wind accompanied by corresponding changes in precipitation but is now used to describe seasonal changes in atmospheric circulation and precipitation associated with annual latitudinal oscillation of the Intertropical Convergence Zone (ITCZ) between its limits to the north and south of the equator. Usually, the term monsoon is used to refer to the rainy phase of a seasonally changing pattern, although technically there is also a dry phase. The term is also sometimes used to describe locally heavy but short-term rains. The major monsoon systems of the world consist of the West African, Asia–Australian, the North American, and South American monsoons. The term was first used in English in British India and neighboring countries to refer to the big seasonal winds blowing from the Bay of Bengal and Arabian Sea in the southwest bringing heavy rainfall to the area. Etymology The etymology of the word monsoon is not wholly ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ephemeral Stream
A stream is a continuous body of surface water flowing within the bed and banks of a channel. Depending on its location or certain characteristics, a stream may be referred to by a variety of local or regional names. Long large streams are usually called rivers, while smaller, less voluminous and more intermittent streams are known as streamlets, brooks or creeks. The flow of a stream is controlled by three inputs – surface runoff (from precipitation or meltwater), daylighted subterranean water, and surfaced groundwater (spring water). The surface and subterranean water are highly variable between periods of rainfall. Groundwater, on the other hand, has a relatively constant input and is controlled more by long-term patterns of precipitation. The stream encompasses surface, subsurface and groundwater fluxes that respond to geological, geomorphological, hydrological and biotic controls. Streams are important as conduits in the water cycle, instruments in groundwater rech ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Calcareous
Calcareous () is an adjective meaning "mostly or partly composed of calcium carbonate", in other words, containing lime or being chalky. The term is used in a wide variety of scientific disciplines. In zoology ''Calcareous'' is used as an adjectival term applied to anatomical structures which are made primarily of calcium carbonate, in animals such as gastropods, i.e., snails, specifically about such structures as the operculum, the clausilium, and the love dart. The term also applies to the calcium carbonate tests of often more or less microscopic Foraminifera. Not all tests are calcareous; diatoms and radiolaria have siliceous tests. The molluscs are calcareous, as are calcareous sponges ( Porifera), that have spicules which are made of calcium carbonate. In botany ''Calcareous grassland'' is a form of grassland characteristic of soils containing much calcium carbonate from underlying chalk or limestone rock. In medicine The term is used in pathology, for example i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lens (geology)
In geology, a lens or lentil is a body of ore or rock that is thick in the middle and thin at the edges, resembling a convex lens in cross-section. To thin out in all directions is to "lens out", also known as "lensing". The adjectives "lenticular" and "lentiform" are used to describe lens-like formations. Lenticle is a synonym for lentil, but may also refer to a fragment of rock that is lens-shaped. "Lenticule" is used for small lentil. A lentil may also refer a minor unit in a formation of rock, similar to a member but not generally spread out over a large geographical area. In this usage, the lentil thins out towards its edges. Lenticular bedding is a special form of rock interbedded mudrock and cross-laminated rippled 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) . ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
_nahe_dem_Weiherdamm_in_Wildbergerhütte.jpg "Click for more on -> Ephemeral Stream")
