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Disappointment Bay Formation
The Disappointment Bay Formation is a Formation (geology), geologic formation in Nunavut, extending from Ellesmere Island in the east to Bathurst Island (Nunavut), Bathurst Island in the west. It preserves fossils dating back to the Devonian Period (geology), period, primarily of invertebrates. Fossil Content Fish Vertebrate remains are rare in this formation. Indeterminate spine fragments are found throughout the Lowther Island off-reef limestones but are rare. A 2-centimeter wide fragment found in the 2 m-level Ammonoidea, ammonoid bed of Young Island (Nunavut), Young Island may represent a Cyathaspididae, cyathaspidid. Invertebrates Plants and algae See also * List of fossiliferous stratigraphic units in Nunavut References * Devonian Nunavut Devonian southern paleotropical deposits {{Nunavut-geo-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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] |
Silicification
In geology, silicification is a petrification process in which silica-rich fluids seep into the voids of Earth materials, e.g., rocks, wood, bones, shells, and replace the original materials with silica (SiO2). Silica is a naturally existing and abundant compound found in organic and inorganic materials, including Earth's crust and mantle. There are a variety of silicification mechanisms. In silicification of wood, silica permeates into and occupies cracks and voids in wood such as vessels and cell walls. The original organic matter is retained throughout the process and will gradually decay through time. In the silicification of carbonates, silica replaces carbonates by the same volume. Replacement is accomplished through the dissolution of original rock minerals and the precipitation of silica. This leads to a removal of original materials out of the system. Depending on the structures and composition of the original rock, silica might replace only specific mineral components ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brachiopod
Brachiopods (), phylum Brachiopoda, are a phylum of trochozoan animals that have hard "valves" (shells) on the upper and lower surfaces, unlike the left and right arrangement in bivalve molluscs. Brachiopod valves are hinged at the rear end, while the front can be opened for feeding or closed for protection. Two major categories are traditionally recognized, articulate and inarticulate brachiopods. The word "articulate" is used to describe the tooth-and-groove structures of the valve-hinge which is present in the articulate group, and absent from the inarticulate group. This is the leading diagnostic skeletal feature, by which the two main groups can be readily distinguished as fossils. Articulate brachiopods have toothed hinges and simple, vertically-oriented opening and closing muscles. Conversely, inarticulate brachiopods have weak, untoothed hinges and a more complex system of vertical and oblique (diagonal) muscles used to keep the two valves aligned. In many brachiopods, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anatomical Terms Of Location
Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position provides a definition of what is at the front ("anterior"), behind ("posterior") and so on. As part of defining and describing terms, the body is described through the use of anatomical planes and anatomical axes. The meaning of terms that are used can change depending on whether an organism is bipedal or quadrupedal. Additionally, for some animals such as invertebrates, some terms may not have any meaning at all; for example, an animal that is radially symmetrical will have no anterior surface, but can still have a description that a part is close to the middle ("proximal") or further from the middle ("distal"). International organisations have determined vocabularies that are often used as standard vocabularies for subdisciplines of anatom ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solemya
''Solemya'' is a genus of saltwater clams, marine bivalve mollusks in the family Solemyidae, the awning clams. ''Solemya'' is the type genus of the family Solemyidae. Description The shell valves of species in this genus are fragile and subcylindrical in shape; there are no hinge teeth. The shell has a persistent thin periostracum which extends beyond the valve margins, hence the common name "awning clams". These clams have chemosynthetic bacterial symbionts that produce their food. The bacteria live within their gill cells, and produce energy by oxidizing hydrogen sulfide, which they then use to fix carbon dioxide via the Calvin cycle. This symbiosis has been best-studied in the Atlantic species '' S. velum'' and the Pacific species '' S. reidi''. Species Species within the genus ''Solemya'' include: * '' Solemya africana'' * '' Solemya atacama'' * '' Solemya australis'' * ''Solemya borealis'' * '' Solemya elarraichensis'' * ''Solemya flava'' * ''Solemya moretonensis'' * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lucinidae
Lucinidae, common name hatchet shells, is a family of saltwater clams, marine bivalve molluscs. These bivalves are remarkable for their endosymbiosis with sulphide-oxidizing bacteria. Characteristics The members of this family have a worldwide distribution. They are found in muddy sand or gravel at or below low tide mark. But they can also be found at bathyal depths. They have characteristically rounded shells with forward-facing projections. The shell is predominantly white and buff and is often thin-shelled. The shells are equivalve with unequal sides. The umbones (the apical part of each valve) are just anterior to mid-line. The adductor scars are unequal: the anterior are narrower and somewhat longer than the posterior. They are partly or largely separated from the pallial line. The valves are flattened and etched with concentric or radial rings. Each valve bears two cardinal and two plate-like lateral teeth. These molluscs do not have siphons but the extremely long foot make ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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