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Micraster
''Micraster'' is an extinct genus of echinoids from the Late Cretaceous to the early Eocene. Its remains have been found in Africa, Antarctica, Europe, and North America. Micraster was an infaunal echinoid living in a burrow below the sediment surface. The test is clearly bilateral and there is a deep anterior groove to take in water containing organic particles to the mouth. The tube feet keep a supply of nutrient-laden water moving into the burrow. The anus has a waste tube behind it. Continuous evolution In the classic text '' The Science of Life'' (1931), H. G. Wells Herbert George Wells (21 September 1866 – 13 August 1946) was an English writer, prolific in many genres. He wrote more than fifty novels and dozens of short stories. His non-fiction output included works of social commentary, politics, hist ..., Julian Huxley and G. P. Wells use ''Micraster'' as an example of a fossil whose continuous evolution can be traced over some 10 million years through 450� ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Micraster Elevatus
''Micraster'' is an extinct genus of echinoids from the Late Cretaceous to the early Eocene. Its remains have been found in Africa, Antarctica, Europe, and North America. Micraster was an infaunal echinoid living in a burrow below the sediment surface. The test is clearly bilateral and there is a deep anterior groove to take in water containing organic particles to the mouth. The tube feet keep a supply of nutrient-laden water moving into the burrow. The anus has a waste tube behind it. Continuous evolution In the classic text ''The Science of Life'' (1931), H. G. Wells, Julian Huxley and G. P. Wells use ''Micraster'' as an example of a fossil whose continuous evolution can be traced over some 10 million years through 450–500 feet of chalk beds of the Late Cretaceous. They point out: :"During this long period the fossil Micrasters are so abundant that hundreds of thousands can be collected and a gradual evolution can be traced as we pass upward. The changes are apparently ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Micraster
''Micraster'' is an extinct genus of echinoids from the Late Cretaceous to the early Eocene. Its remains have been found in Africa, Antarctica, Europe, and North America. Micraster was an infaunal echinoid living in a burrow below the sediment surface. The test is clearly bilateral and there is a deep anterior groove to take in water containing organic particles to the mouth. The tube feet keep a supply of nutrient-laden water moving into the burrow. The anus has a waste tube behind it. Continuous evolution In the classic text '' The Science of Life'' (1931), H. G. Wells Herbert George Wells (21 September 1866 – 13 August 1946) was an English writer, prolific in many genres. He wrote more than fifty novels and dozens of short stories. His non-fiction output included works of social commentary, politics, hist ..., Julian Huxley and G. P. Wells use ''Micraster'' as an example of a fossil whose continuous evolution can be traced over some 10 million years through 450� ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spatangoida
The heart urchins or Spatangoida are an order (biology), order of sea urchins. Their body is a somewhat elongated oval in form, and is distinguished by the mouth being placed towards one end of the animal, and the anus towards the other. As a result, heart urchins, unlike most other sea urchins, are bilaterally symmetrical, and have a distinct anterior surface. The presence and position of the mouth and anus typically give members of this group the distinct "heart" shape from which they get their name. Heart urchins have no feeding lantern, and often have petaloids sunk into grooves. They are a relatively diverse order, with a number of varying species. Taxonomy According to World Register of Marine Species : * suborder Brissidina Stockley, Smith, Littlewood, Lessios & MacKenzie-Dodds, 2005 ** family Asterostomatidae Pictet, 1857 ** family Brissidae Gray, 1855 ** family Palaeotropidae Lambert, 1896 ** superfamily Spatangoidea Fischer, 1966 *** family Eupatagidae Lambert, 1905 * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
