As reported by The Insider, scientists from Tel Aviv University and the Nanjing Institute of Geology and Palaeontology of the Chinese Academy of Sciences figured out how extinct cicada-like insects, preserved in Burmese amber about 100 million years ago, fed. The study was published in the journal Insects.
The authors studied 13 specimens from amber found in northern Myanmar — adult insects and larvae. In some, the proboscis reached the hind legs; in others, it was more than twice as long as the body, and in many cases it was preserved bent, indicating its flexibility in life.
To see the internal structure, the specimens were scanned at synchrotrons in Germany and Switzerland, and high-resolution 3D images were obtained. The scanning showed that the small folds on the last segment of the proboscis are true wave-like bends of the covering of uniform thickness, not a surface pattern.
According to the authors, such a corrugated part functioned like a bendable tube: it bent easily but did not break or flatten. Inside the proboscis were thin piercing bristles that the insects used to puncture the plant; according to the researchers, this helped them get into deep cracks in the bark and reach the sap inside the tree. In modern relatives of these insects, the proboscis points backward and is too rigid, whereas in ancient ones its tip could bend forward and enter a crack in the bark.
The authors also write that the tip of the proboscis, as the bristles extended, opened like a wall plug under a screw and likely anchored the insect in the bark. Aphids of the genus Stomaphis feed in a similar way today, and this type of feeding itself, the researchers suggest, may have developed in Cretaceous forests, where coniferous trees often burned and therefore developed thicker bark on their trunks. The version involving nectar is rejected by the authors: no noticeable accumulations of pollen were found on the bodies, and similar corrugated mouthparts independently appeared in other Cretaceous insects as well, including ancient scorpionflies with long proboscises.
In addition, the scientists proposed combining two extinct families — Neazoniidae, known mainly from larvae, and Mimarachnidae, described mainly from adults, since both groups have the unusual proboscis. The same study describes a new species, Cretodorus noonoo: the body length of an adult male reaches 8.7 mm, and its proboscis is twice as long.
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