According to China Science Daily, Cai Chenyang, associate researcher at the Nanjing Institute of Geology and Paleontology of the Chinese Academy of Sciences, and pan Yanhong, a researcher, led a team to carry out research and uncovered the secret of the true color of insects nearly 100 million years ago. The results were published online on July 1 in the Proceedings of the Royal Society, Series B, providing a new perspective on the insects that coexisted with dinosaurs in the Cretaceous rainforest.
There are three main sources of color in nature: bioluminescence, pigment color (chemical color), and structural color (physical color). Structural colors are the purest and most intense colors in nature, usually produced by the action of biological nano-optical structures and natural light.
"Structural colors in fossils can provide important evidence for visual communication between organisms and the functional evolution of colors." Cai Chenyang told China Science Daily. However, it may be that evidence of primitive structural colors in geological history is extremely rare due to the fact that structural colors are easily lost in long-term fossil burials.
To this end, Cai Chenyang and Pan Yanhong led the team to conduct a large number of systematic studies on the metal-colored insects in Cretaceous Burmese amber, and found that pure and intense colors can be directly preserved on the surface of a variety of insect bodies. The research team selected 35 beautifully preserved insect fossils with metallic luster from the mid-Cretaceous specimens (about 100 million years ago), including 3 orders (Hymenoptera, Coleoptera and Diptera), at least 7 families, the vast majority of which belong to the Hymenoptera cynoflagellaceae. Through ultra-microanalysis of one of the fossil green bee specimens, the team confirmed that the multilayer reflective film is the direct cause of structural color, which also represents the most common form of structural color in nature.
Cai Chenyang introduced that this discovery directly proves that ultra-micro and nano-scale optical elements can be stably preserved in long-term geological history, negates the view that insect metallic color cannot be preserved in Mesozoic fossils, and is of great significance for understanding the evolution of the ecological function of early insect structural color.
It is worth mentioning that the seemingly permanently preserved colored metallic structural color in Burmese amber is not unchanged. If any small part of the structure of the amber insect is damaged in the process of preliminary preparation (such as cutting, sanding and polishing), and comes into contact with air or moisture, its color will become a single silver in the short term, but the metallic luster can still be preserved, and this change is irreversible.
"The discovery of this phenomenon has important reference value for the revelation of the causes of the formation of silver insects and the identification and description of early insect characteristics." Cai Chenyang said, "The possibility of structural colors involved in insect thermal regulation cannot be completely ruled out. Therefore, the structural colors of different colors appear in different species of insects, to some extent suggesting that complex ecological relationships already existed in the forests of the middle Cretaceous Period. (Shen Chunlei)