European land mammal age
|Epoch||ICS age||ELMMZ||Age (Ma)|
|Subdivision of the Paleogene period into European Land Mammal Mega Zones (ELMMZ).|
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.
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.
Neogene European mammal zonesEdit
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 biozonesEdit
- 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.