أزمنة الثدييات البرية الأوروبية
| النطاق | ICS العمر | ELMMZ | العمر (Ma) |
|---|---|---|---|
| الميوسين Miocene |
الأكيتاني Aquitanian |
الآجني Agenian |
أحدث |
| الأوليگوسين Oligocene |
الخاتي | Arvernian | 23.03-29.2 |
| الروپلي Rupelian | |||
| Suevian | 29.2-33.8 | ||
| الهيدوني | 33.8-37.2 | ||
| الإيوسين Eocene |
الپريابوني | ||
| البارتوني | Robiacian | 37.2–42.7 | |
| اللوتتي Lutetian | |||
| الگايزلتالي | 42.7-48.5 | ||
| Grauvian | 48.5–50.8 | ||
| الإپرسي Ypresian | |||
| Neustrian | 50.8-55.0 | ||
| الپاليوسين Paleocene |
الثانتي Thanetian | ||
| Cernaysian | 55.0-55.9 | ||
| تقسيم العصر الپاليوجيني إلى المناطق الكبرى للثدييات البرية الأوروپية (ELMMZ). | |||
المناطق الكبرى للثدييات البرية الأوروپية European Land Mammal Mega Zones(اختصارها: ELMMZ، ويشيع تسميتها أزمنة الثدييات البرية الأوروبية European land mammal ages أو ELMA) هي مناطق في الطبقات الصخرية يوجد فيها تجمعات معينة من الأحافير (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.[1]
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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 chance 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).[2]
Neogene European mammal zones
قالب:Neogene ELMA European Land Mammal Mega Zones most often have their bases at first appearances (FAD, First Appearance Date) of a certain species or genus. The numbers are higher for younger zones. Due to a redefinition of the boundary between the Neogene and Quaternary periods, MN 17 is now in fact considered a Quaternary biozone.
Other continental mammalian biozones
- Asian land mammal age
- Mammal Paleogene zone
- North American land mammal age
- South American land mammal age
المراجع
Notes
- ^ According to Steininger (1999), it is better to just use ELMMZ's in a biostratigraphic sense
- ^ Mammal Paleogene zones, The Paleobiology Database
Literature
- Koufos, G.D.; Kostopoulos, D.S. & Vlachou, T.D. (2005). '"Neogene/Quaternary mammalian migrations in Eastern Mediterranean", Belgian Journal of Zoology 135(2): pp. 181–190.
- Lindsay, Everett (October 1997). "Eurasian mammal biochronology: an overview". Palaeogeography, Palaeoclimatology, Palaeoecology. 133 (3–4): 117–128. doi:10.1016/S0031-0182(97)00083-7.
- Mein, P. (1975). Report on activity RCMNS-Working groups, 1971–1975, pp. 78–81, Bratislava.
- Rose, Kenneth D. (2006). The beginning of the age of mammals. Baltimore, Md.: Johns Hopkins Univ. Press. ISBN 978-0801884726.
- Steininger, F.F. (1999). "Chronostratigraphy, Geochronology and Biochronology of the Miocene "European Land Mammal Mega-Zones" (ELMMZ) and the Miocene "Mammal Zones (MN-Zones)"". In Rössner, G. E.; Heissig, K. (eds.). The Miocene land mammals of Europe. München: Pfeil. pp. 9–24. ISBN 3-931516-50-4.