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It consists of seventeen consecutive zones (numbered MN 1 through MN 18; MN 7 and 8 have been joined into MN 7/8 zone) defined through reference faunas, well-known sites that other localities can be correlated with. MN 1 is the earliest zone, and MN 18 is the most recent. The MN zones are complementary with the MP zones in the Paleogene.
Titanotheres have since been found above the Chadron Formation, leaving the definition of the age uncertain. [1]: 240 Since NAMLs are not tied to stratigraphic sections, they are not true chronostratigraphic stages, so some authors place quotes around "Ages". [1]: 240 [4]: 943 [8]
Biostratigraphy is the branch of stratigraphy which focuses on correlating and assigning relative ages of rock strata by using the fossil assemblages contained within them. [1] The primary objective of biostratigraphy is correlation , demonstrating that a particular horizon in one geological section represents the same period of time as another ...
In biostratigraphy, biostratigraphic units or biozones are intervals of geological strata that are defined on the basis of their characteristic fossil taxa, as opposed to a lithostratigraphic unit which is defined by the lithological properties of the surrounding rock. A biostratigraphic unit is defined by the zone fossils it contains. These ...
It consists of thirty consecutive zones (numbered MP 1 through MP 30; MN 8 and 9 have been joined into MN 8 + 9 zone; and MP 17 zone is split into two zones - MP 17A and MP 17B zone) defined through reference faunas, well-known sites that other localities can be correlated with.
It is preceded by MN 3 and followed by MN 5; together, these three zones form the Orleanian age of the middle Miocene. [1] This zone starts within magnetostratigraphic chron C5Dr, at 18 million years ago, and ends within chron C5Cr, at 17.0 million years ago, although some different correlations have been proposed. [2]
Relative dating by biostratigraphy is the preferred method in paleontology and is, in some respects, more accurate. [1] The Law of Superposition, which states that older layers will be deeper in a site than more recent layers, was the summary outcome of 'relative dating' as observed in geology from the 17th century to the early 20th century.
In biostratigraphy, a subdiscipline of geology, a taxon-range zone is the zone between the highest and the lowest stratigraphic occurrence of a taxon.Taxon-range zones are one of the fundamental biozones used in biostratigraphy and are named after the taxon whose range they describe.