The pollen record discussed in this paper shows a clear differ-
ence between Oligocene mesothermic elements (Alnus, Cas-
tanea) and Miocene thermophilous elements. The Oligocene
record presented here is well constrained in time (between
26 and 24 Ma) but lacks supplemental samples to definitely
state that regional vegetation is represented. However it com-
pares well with previous studies depicting warm temperate
paleoenvironments in Thailand between the Late Oligocene
and early Miocene (Songtham et al., 2003, 2005). Further
information come from leaf fossils of the genus Mangifera
(Anacardiaceae) recorded in Late Oligocene-early Miocene
sandstones and claystones of the Li basin (Sawangchote et
al., 2009). Together with palynological data, these remains
suggest various mixed forested environments. A review of