In nature, some plants have a phenomenon similar to "sleeping".

Chinese paleontologists have discovered the secret that plants love to "sleep" from fossils dating back 250 million years. The achievement was published online in the internationally renowned journal "Current Biology" on February 16, Beijing time.

In nature, some plants have a phenomenon similar to "sleeping"-their leaves unfold during the day and close or droop at night, which is called "nocturnal sensitivity of plants" in the academic circle. This periodic movement of leaves has always attracted the attention of the academic community, but due to the lack of fossil evidence, the academic community has so far known little about the origin and evolution of plant "sleeping" behavior.

Feng Zhuo's team from the Institute of Paleontology of Yunnan University confirmed for the first time that plants in ancient times also had nocturnal sensitivity from the fossils of large feathered ferns 250 million years ago. The fossil was unearthed in Qujing, Yunnan.

The team observed that on the leaves of the plant, there is a new type of insect bite structure, and these bite marks are arranged symmetrically on both sides of the midrib of the leaf. In terms of shape and size, the bite marks on one side of the midrib were always slightly different from those on the other side, and the closer to the midrib or the base of the leaf, the more obvious the difference between the bite marks on both sides.

After a comparative study with a large number of living plants, the team found that the "worm eye" structure on these fossils was actually consistent with the structure left by the insects after the leaves of the living plants were closed at night. "So we infer that some insects gnawed away the 'sleeping' large-feathered fern with closed leaves. It is rare that this plant fossil has been well preserved to this day." Feng Zhuo said.

This discovery pushes back the origin of plant nocturnal sensitivity to 250 million years ago.

(Original title "Fossils from 250 million years ago reveal the secret that plants love to "sleep"")