Introduction

Global palaeoclimate fluctuated cyclically during the Oligocene–Holocene, generally (though never irreversibly) deteriorating until the Pleistocene, which was characterised by widespread glaciation.

Eurasian palaeogeography was modified not only by associated (climatically induced) cyclic fluctuations in sea-level (glacio-eustasy) but also by mountain-building (tectonism) associated with the convergence between Arabia and Eurasia and the closure of the formerly intervening ocean known, after the daughter of the mythological earth-goddess Gaia, as Tethys (Suess, 1893). While Tethys, also known as the Tethyan Ocean or Seaway, was in existence, marine faunas were able to migrate between the Indo-Pacific and Mediterranean, and when it ceased to exist, terrestrial faunas were able to migrate between Africa and Eurasia.

This paper attempts to collate and integrate all the available marine invertebrate (chiefly foraminiferal) and associated evidence pertinent to the stratigraphy and palaeogeography of Western Eurasia over the critical Oligocene–Miocene interval, to describe the palaeogeographic evolution of the area during this time in the form of a series of time-slice maps, and to consider the consequences for terrestrial vertebrate migration.

Stratigraphy

The best-fit stratigraphic correlation that forms the basis for the time-slice identification and palaeogeographic mapping of the present paper is given in Fig. 14.1. Chronostratigraphy (global (Mediterranean)and regional (Indo-Pacific) stages), biostratigraphy (planktonic foraminiferal, calcareous nannoplankton and mammalian zones (and mammalian stages)), magnetostratigraphy, regional (Indian/Pakistani, Iranian and Paratethyan) lithostratigraphy, regional (Paratethyan) and global sequence stratigraphy, climatostratigraphy and palaeotemperature are all shown.

For the sake of consistency, I have attempted wherever possible to use biostratigraphy for the purposes of age assignment and stratigraphic correlation.