『Abstract
　Removing the Tertiary and Quaternary Periods whilst conserving the Paleogene and Neogene Periods in The Geological Timescale 2004 caused a storm of protest. One response was to advocate restoring an enlarged Quaternary and consigning the Neogene to a minor role within the Tertiary. Amongst an array of practical, traditional, sentimental and anthropocentric reasons for this response, the one hard-core justification was that the rigidly nested hierarchy of the geological timescale must be preserved.
　The central objective of this paper is conserving the historically legitimate, Miocene-present, Neogene Period and System. There are two options for conserving the Quaternary concurrently with the Neogene: (i) an inclusive compromise in a flexible hierarchy, and (ii) an upgrading of Pliocene and Pleistocene divisions to the level of epoch. In the inclusive compromise there coexist alternative pathways through the hierarchical ranks. Thus geohistorians and biohistorians have two options for traversing the hierarchy from era to age, as in this example using the hierarchical positioning of the Calabrian Age and Stage:
either Cenozoic [era]⇔Neogene [period]⇔Pleistocene [epoch]⇔Calabrian [age]
or Cenozoic [era]⇔Quaternary [subera]⇔Pleistocene [epoch]⇔Calabrian [age]
We reaffirm that the inclusive compromise is entirely viable. In so doing we (i) challenge the necessity of the rigidly nested hierarchy, which should be capable of a little flexibility; (ii) reject all analogies of the arbitrary and conventional chronostratigraphic hierarchy with three natural biological hierarchies; (iii) reaffirm the integrity of the Neogene extending to the present; and (iv) see no reason to doubt the harmonious coexistence of the two options preserving the Quaternary and Neogene traditions in an orderly working and stable time scale.
　In the alternative schema conserving the Neogene, divisions of the Pliocene and Pleistocene are upgraded, so that the Late Pleistocene, Early Pleistocene and Late Pliocene Epochs comprise the Quaternary Subperiod, itself equivalent to Late Neogene. The inflexibly nested hierarchy is preserved but the Tertiary is lost.

Keywords: chronostratigraphic classification; hierarchy; Cenozoic; Neogene; Quaternary』

Contents
1. Introduction
2. The Neogene tradition
　2.1. Origins and development of the Neogene Period
　2.2. The rise of planktonic foraminiferal biostratigraphy in the Neogene tradition
　2.3. Neogene in the pelagic realm: progress in the deep-marine
3. Chronostratigraphy and Neogene geohistory and biohistory
　3.1. Chronostratigraphic classification and nomenclature are in the framework category
　3.2. Challenging the necessity of the rigidly nested chronostratigraphic hierarchy
　3.3. The biological hierarchies are natural and discoverable...
　3.4. The chronostratigraphic hierarchy is arbitrary and conventional
4. The integrity of the Neogene and its natural divisions
5. The arguments by Stephen Walsh
6. Conclusion: two options for conserving the historically legitimate Neogene
Acknowledgments
Appendix A. Moritz Hornes（oの頭に¨） and the origins and meaning of the “Neogene”
Note added in proof
References