The top of the Langhian stage ( the base of the Serravallian stage ) is at the first occurrence of fossils of the nannoplankton species " Sphenolithus heteromorphus " and is located in magnetic chronozone C5ABr.
12.
The top of the Maastrichtian stage is defined to be at the iridium anomaly at the Cretaceous Paleogene boundary ( K Pg boundary ), which is also characterised by the extinction of many groups of life, such as certain foraminifers and calcareous nannoplankton, all ammonites and belemnites, etc.
13.
The top of the Chattian stage ( which is the base of the Aquitanian stage, Miocene series and Neogene system ) is at the first appearance of foram species " Paragloborotalia kugleri ", the extinction of calcareous nannoplankton species " Reticulofenestra bisecta " ( which forms the base of nannoplankton biozone NN1 ), and the base of magnetic C6Cn . 2n.
14.
The top of the Chattian stage ( which is the base of the Aquitanian stage, Miocene series and Neogene system ) is at the first appearance of foram species " Paragloborotalia kugleri ", the extinction of calcareous nannoplankton species " Reticulofenestra bisecta " ( which forms the base of nannoplankton biozone NN1 ), and the base of magnetic C6Cn . 2n.
15.
The base of the Aquitanian ( also the base of the Miocene system ) is defined as the place in the stratigraphic column at the first appearance of foram species " Paragloborotalia kugleri ", the extinction of calcareous nannoplankton species " Reticulofenestra bisecta " ( which forms the base of nannoplankton biozone NN1 ), and the base of magnetic chronozone C6Cn . 2n.
16.
The base of the Aquitanian ( also the base of the Miocene system ) is defined as the place in the stratigraphic column at the first appearance of foram species " Paragloborotalia kugleri ", the extinction of calcareous nannoplankton species " Reticulofenestra bisecta " ( which forms the base of nannoplankton biozone NN1 ), and the base of magnetic chronozone C6Cn . 2n.
