Fossil woods of Cryptocarya (Lauraceae) from the middle Miocene of Southwest China

Abstract

The structure of lauraceous fossil woods from the middle Miocene deposits of the Dajie Formation of Ninger County, Yunnan Province, China has been studied. The occurrence of wide (> 7 seriate) rays in combination with the presence of scalariform perforation plates, the oil/mucilage cells in rays, axial parenchyma and among fibers as well as some other traits allow us to attribute the fossil woods to the extant genus Cryptocarya. We describe the woods as a new species C. latiradiata R. Zhang, T. Su & A. A. Oskolski sp. nov. (Lauraceae). This is an important improvement in the fossil record of Cryptocarya showing that this genus was widely ranged across southern China in the middle Miocene. The occurrence of the fossil woods of such termophyllous genus as Cryptocarya in the Dajie Formation suggests that this middle Miocene climate in southern Yunnan was frostless. This result is consistent with other evidence for the warm environment caused by complex topographic structures in this region since the middle Miocene linked to the successive uplift of the Tibetan Plateau and the Ailao Mountains. Particularly, it suggests that the Ailao Mountains in the middle Miocene were high enough to weaken the influence of the Asian Winter Monsoon on the territory of Yunnan.