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The European Land Mammal Mega Zones (abbreviation: ELMMZ, more commonly known as European land mammal ages or ELMA) are zones in rock layers that have a specific assemblage of fossils (biozones) based on occurrences of fossil assemblages of European land mammals. These biozones cover most of the Neogene and Paleogene systems (i.e. rock layers which are 65.5 to 2.588 million years old). In cases when fossils of mammals are abundant, stratigraphers and paleontologists can use these biozones as a more practical regional alternative to the stages of the official ICS geologic timescale. European Land Mammal Mega Zones are often also confusingly referred to as ages, stages, or intervals.〔According to Steininger (1999), it is better to just use ELMMZ's in a biostratigraphic sense〕 ==Biostratigraphic methods== Mammal zones were, like all biozones, established using geographic place names where fossil materials were obtained. The basic unit of measure is the first/last boundary statement. This shows that the first appearance event of one taxon is known to predate the last appearance event of another. If two taxa are found in the same fossil quarry or at the same stratigraphic horizon, then their age-range zones overlap. The terrestrial stratigraphy of the Cenozoic is more difficult than that of marine deposits. The geologic timescale of the ICS is therefore based on marine fossils, that don't occur in terrestrial sediments. This makes the correlation of terrestrial deposits with the ICS timescale often difficult. Correlation is possible when marine deposits interfinger with terrestrial deposits (resulting from a series of transgressions and regressions of the sea during deposition), but this isn't the case everywhere. A fine stratigraphic division of the terrestrial record can in most places only be made using fossils of land species. Small mammals are often the best choice as they are quite abundant in the terrestrial record, especially their teeth. Teeth have an even better change of preservation than bones. The European mammalian biozones were established for the Paleogene (8 zones) and Neogene (7 zones) separately. Some of these, especially for the Neogene, were already established in the 19th century. The Villafranchian was, for example, introduced by Lorenzo Pareto in 1865. A finer subdivision was established by Pierre Mein in 1975, who divided the Neogene in 17 zones, known as the MN zonation, indicated by the letters MN (Mammal Neogene) and a number. Similarly, a more detailed subdivision for the Paleogene period was established. There are 30 such Mammal Paleogene zones (MP1 to MP30, numbered from old to young).〔(Mammal Paleogene zones ), The Paleobiology Database〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「European land mammal age」の詳細全文を読む スポンサード リンク
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