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出典:『Wikipedia』 (2011/01/30 18:21 UTC 版)

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Paleodictyon is a pattern, usually interpreted to be a burrow, which appears in the geologic record beginning in the Cambrian and in modern ocean environments. Both irregular and regular nets are known throughout the stratigraphic range of Paleodictyon, but it is the striking regular honeycomb pattern of some forms such as P. carpathecum which make it fascinating and widely studied. Individual mesh elements may be millimeters to centimeters, and entire mesh patterns can cover areas up to a square meter. The edges or threads that make up the mesh are usually cylindrical or ellipsoid in cross-section, and some forms have vertical tubes connecting the mesh upwards to the sediment-water interface. Dolf Seilacher proposed in 1977 that it may be a trap for food, a mechanism for farming, or a foraging path. Alternatively, it has been suggested that it may be a cast of a xenophyophoran protist.