Cretaceous conifer woods of Korea: Occurrences and palaeobiological implications

Abstract

Six different types of conifer wood were recovered from Cretaceous terrestrial deposits in six sites in Korea: Xenoxylon latiporosum (Cramer) Gothan from the Nakdong Formation (Hauterivian to Barremian), Agathoxylon togeumense Oh, Kim, Paik and Lim, sp. nov. and Agathoxylon kiiense (Ogura) Oh, Kim, Paik and Lim from the Togeum Formation (Albian), Agathoxylon byeongpungense (Kim et al.) Oh, Kim, Paik and Lim from the Donghwachi Formation (Aptian to Albian), Brachyoxylon sp. from the Dogyedong Formation (Aptian to Albian), and Taxodioxylon nihongii Nishida and H. Nishida from the two islands' deposits in Yeosu City which have not yet been classified lithostratigraphically, but can be dated as Campanian to Maastrichtian. Two palaeophytogeographic zones are known from the Lower Cretaceous of NE Asia. In addition, there is a Mixed-type flora with floristic elements from the northern and southern phytogeographic regions. The Korean Peninsula has been regarded to have hosted a Mixed-type flora during the Early Cretaceous. The fossil wood taxa described here indicate that the palaeovegetation in the southern Korean Peninsula shows a transition from a Mixed-type flora largely dominated by Tetori-type taxa in the early Early Cretaceous to a Mixed-type flora dominated by Ryoseki-type taxa in the late Early Cretaceous. The Late Cretaceous flora of the Korean Peninsula was similar to Ryoseki-type flora of the Early Cretaceous. Pinaceous fossil wood has not been recorded yet and only one poorly preserved dicotyledonous fossil wood has been reported from the southern Korean Peninsula. The Korean Peninsula and the adjacent regions thus show differences in the composition of the fossil wood flora suggesting differences in the composition of the palaeovegetation in these regions.