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Calcimicrobe
Characteristic of the Neoproterozoic and Cambrian periods, the heterogeneous group called calcimicrobes are calcareous colonial microfossils, which include many morphologically dissimilar organisms, whose effect in massive aggregations, in association with shelly metazoans, was to lay down the earliest recognizable reef systems: compare Archaeocyathids. The earliest recognizable patch reefs date to the Tommotian. Individual calcimicrobes laid down calcium carbonate in tubules, threads, chambered structures and other forms. The term calcimicrobe is useful in recreating the paleoecology Paleoecology (also spelled palaeoecology) is the study of interactions between organisms and/or interactions between organisms and their environments across geologic timescales. As a discipline, paleoecology interacts with, depends on and informs ... of these systems. The term was first applied by N.P. James and D.I. Gravestock in 1990. References *James,N.P. and D.I. Gravestock. 1990. "Lower Cam ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neoproterozoic
The Neoproterozoic Era is the unit of geologic time from 1 billion to 538.8 million years ago. It is the last era of the Precambrian Supereon and the Proterozoic Eon; it is subdivided into the Tonian, Cryogenian, and Ediacaran periods. It is preceded by the Mesoproterozoic Era and succeeded by the Paleozoic Era of the Phanerozoic Eon. The most severe glaciation known in the geologic record occurred during the Cryogenian, when ice sheets may have reached the equator and formed a "Snowball Earth". The earliest fossils of complex multicellular life are found in the Ediacaran Period. These organisms make up the Ediacaran biota, including the oldest definitive animals in the fossil record. According to Rino and co-workers, the sum of the continental crust formed in the Pan-African orogeny and the Grenville orogeny makes the Neoproterozoic the period of Earth's history that has produced most continental crust. Geology At the onset of the Neoproterozoic the supercontinent Rod ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cambrian
The Cambrian Period ( ; sometimes symbolized Ꞓ) was the first geological period of the Paleozoic Era, and of the Phanerozoic Eon. The Cambrian lasted 53.4 million years from the end of the preceding Ediacaran Period 538.8 million years ago (mya) to the beginning of the Ordovician Period mya. Its subdivisions, and its base, are somewhat in flux. The period was established as "Cambrian series" by Adam Sedgwick, who named it after Cambria, the Latin name for 'Cymru' (Wales), where Britain's Cambrian rocks are best exposed. Sedgwick identified the layer as part of his task, along with Roderick Murchison, to subdivide the large "Transition Series", although the two geologists disagreed for a while on the appropriate categorization. The Cambrian is unique in its unusually high proportion of sedimentary deposits, sites of exceptional preservation where "soft" parts of organisms are preserved as well as their more resistant shells. As a result, our understanding of the Cambrian ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Animal
Animals are multicellular, eukaryotic organisms in the Kingdom (biology), biological kingdom Animalia. With few exceptions, animals Heterotroph, consume organic material, Cellular respiration#Aerobic respiration, breathe oxygen, are Motility, able to move, can Sexual reproduction, reproduce sexually, and go through an ontogenetic stage in which their body consists of a hollow sphere of Cell (biology), cells, the blastula, during Embryogenesis, embryonic development. Over 1.5 million Extant taxon, living animal species have been Species description, described—of which around 1 million are Insecta, insects—but it has been estimated there are over 7 million animal species in total. Animals range in length from to . They have Ecology, complex interactions with each other and their environments, forming intricate food webs. The scientific study of animals is known as zoology. Most living animal species are in Bilateria, a clade whose members have a Symmetry in biology#Bilate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reef
A reef is a ridge or shoal of rock, coral or similar relatively stable material, lying beneath the surface of a natural body of water. Many reefs result from natural, abiotic processes— deposition of sand, wave erosion planing down rock outcrops, etc.—but there are also reefs such as the coral reefs of tropical waters formed by biotic processes dominated by corals and coralline algae, and artificial reefs such as shipwrecks and other anthropogenic underwater structures may occur intentionally or as the result of an accident, and sometimes have a designed role in enhancing the physical complexity of featureless sand bottoms, to attract a more diverse assemblage of organisms. Reefs are often quite near to the surface, but not all definitions require this. Earth's largest coral reef system is the Great Barrier Reef in Australia, at a length of over . Biotic There is a variety of biotic reef types, including oyster reefs and sponge reefs, but the most massive and w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Archaeocyatha
Archaeocyatha (or archaeocyathids 'ancient cups') is a taxon of extinct, sessile, reef-building marine sponges that lived in warm tropical and subtropical waters during the Cambrian Period. It is believed that the centre of the Archaeocyatha origin is now located in East Siberia, where they are first known from the beginning of the Tommotian Age of the Cambrian, 525 million years ago ( mya). In other regions of the world, they appeared much later, during the Atdabanian, and quickly diversified into over a hundred families. They became the planet's very first reef-building animals and are an index fossil for the Lower Cambrian worldwide. Preservation The remains of Archaeocyatha are mostly preserved as carbonate structures in a limestone matrix. This means that the fossils cannot be chemically or mechanically isolated, save for some specimens that have already eroded out of their matrices, and their morphology has to be determined from thin cuts of the stone in which th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paleoecology
Paleoecology (also spelled palaeoecology) is the study of interactions between organisms and/or interactions between organisms and their environments across geologic timescales. As a discipline, paleoecology interacts with, depends on and informs a variety of fields including paleontology, ecology, climatology and biology. Paleoecology emerged from the field of paleontology in the 1950s, though paleontologists have conducted paleoecological studies since the creation of paleontology in the 1700s and 1800s. Combining the investigative approach of searching for fossils with the theoretical approach of Charles Darwin and Alexander von Humboldt, paleoecology began as paleontologists began examining both the ancient organisms they discovered and the reconstructed environments in which they lived. Visual depictions of past marine and terrestrial communities have been considered an early form of paleoecology. Overview of paleoecological approaches * Classic paleoecology uses data from ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microfossils
A microfossil is a fossil that is generally between 0.001 mm and 1 mm in size, the visual study of which requires the use of light or electron microscopy. A fossil which can be studied with the naked eye or low-powered magnification, such as a hand lens, is referred to as a macrofossil. Microfossils are a common feature of the geological record, from the Precambrian to the Holocene. They are most common in deposits of marine environments, but also occur in brackish water, fresh water and terrestrial sedimentary deposits. While every kingdom of life is represented in the microfossil record, the most abundant forms are protist skeletons or microbial cysts from the Chrysophyta, Pyrrhophyta, Sarcodina, acritarchs and chitinozoans, together with pollen and spores from the vascular plants. Overview A microfossil is a descriptive term applied to fossilized plants and animals whose size is just at or below the level at which the fossil can be analyzed by the naked eye ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
