According to the news from Nanjing Institute of Geology and paleontology, Chinese Academy of Sciences on June 2, researchers of the Institute have found abundant marine and terrestrial animal and plant fossils in the lower Jurassic Shiti formation in Xiwan basin, Hezhou City, Guangxi, and established the "Xiwan biota" The study found a layer of spectacular mayfly adult colony fossils, revealing the oldest insect mating behavior and the phenomenon of insect resource pulse.
Early Jurassic ecosystem restoration map of Xiwan basin (drawn by yangdinghua, Nanjing Institute of paleontology)
Relevant achievements were published in the journals of Geology and historical biology.
Recently, Zhang Qianqi, a doctoral student of Nanjing Institute of Geology and paleontology, Chinese Academy of Sciences, under the guidance of researcher Wang Bo and researcher zhanghaichun, cooperated with Guangxi Geological Survey Institute to carry out a detailed investigation on the early Mesozoic continental strata in many areas of southern China.
The research team carried out comprehensive research on stratigraphy, paleobotany, paleoentomology and sedimentology. The fossils of shark egg sheaths, insects and plants found in Shiti formation and other fossils reported by predecessors were comprehensively named "Xiwan biota".
At the same time, based on sedimentology and burial analysis, a large number of fossil evidence of "mayflies in heaven and earth" have revealed the oldest insect flight behavior.
According to the researchers, the "marriage flying" behavior refers to the phenomenon that insects reproduce in groups after emergence. This time, the research team found a layer of spectacular mayfly adult colony fossils in the Shiti formation, with hundreds of individuals. These mayflies belong to a new taxon, the dwarf mayflies of Zhang family, and belong to the family mayflies. This is the first discovery of the family ephemeraceae in China, and it is the most well preserved fossil of the family known.
Generally speaking, the living mayfly lives in water for most of its life cycle, and the adult after emergence can only survive for hours to days. In the short adult stage, male individuals form dense clusters in the air. Female individuals must find males to mate in the process of flying into and through the male clusters, and then find a suitable place to lay eggs in order to achieve offspring reproduction.
The group marriage flight of mayflies was only found in the crown group of mayflies in the past. This discovery shows that this complex group marriage flight behavior existed in the trunk group of mayflies in the early Jurassic.
In addition, this study revealed the pulse effect of the oldest insect resources. The research shows that the Jurassic mayflies emerged from the water in a short time, forming a "pulse" of insects from water to land, which may lead to a huge change in the flux of the coastal habitat ecosystem, and then affect the basic ecology and biogeochemical cycle.
The discovery of mayfly clusters in Xiwan biota opened a window for the study of the relationship between Mesozoic aquatic terrestrial ecosystems. The research results also revealed the pulse effect of the oldest known insect resources. The research was jointly supported by the Chinese Academy of Sciences and the National Natural Science Foundation of China.