"It's exceedingly rare to find a specimen where both the insect and the pollen are preserved in a single fossil," Dilcher said. "Aside from the significance as earliest known direct evidence of insect pollination of flowering plants, this specimen perfectly illustrates the cooperative evolution of plants and animals during this time period, during which a true exposition of flowering plants occurred."

Prior to this study, the earliest physical evidence of insect pollination of flowering plants came from Middle Eocene. The age of the new fossil was determined based upon the age of other known fossils in the same location as the fossilized beetle's discovery.

Other authors on the study were Tong Bao and Jianguo Li of the Nanjing Institute of Geology and Palaeontology. Bao is also affiliated with the Institute of Geosciences and Meteorology at the University of Bonn in Germany.

This work was supported in part by the Chinese Academy of Sciences and the National Natural Science Foundation of China.