The early Oligocene is one of the key periods regarding the origin of modern environments and ecosystems on Earth. During this period, major Antarctic ice sheets started to accumulate, global atmospheric CO 2 decreased, and the ocean temperature dropped dramatically from the late Eocene to the early Oligocene (Pälike et al., 2006; Zachos et al., 2001, 2008). Eurasia has undergone significant environmental changes and large tectonic movements. The Paratethys became isolated from the Tethys and marine conditions retreated from Central Asia (Steininger & Wessely, 2000). The uplift of the Qinghai-Tibetan Plateau was linked with aridification in Central Asia (Dupont-Nivet et al., 2008) and contributed to global cooling at the Eocene-Oligocene transition. These tectonic events and associated climate change affected ecosystems in Central Asia.

Dispersed bisaccate pollen grains of Scutasporites nanuki were studied by means of LM, SEM and TEM. Sacci ultrastructure of these pollen grains was rather peculiar. Sacci were like a thin fi lmy fringe attached to the central body near the equator. They were fi lled with sporopollenin elements of irregular shape and various dimensions with equally various cavities between them. Such an ultrastructure is called as spongy. The morphology and ultrastructure of S. nanuki is discussed in the context of the evolution of early conifers.

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