AN international team led by Chinese researchers has uncovered an early insect species dating back roughly 324 million years that displays both aquatic and terrestrial features, providing direct evidence of how insects gradually made the transition from water to land.

The fossil specimen, named Chosha praecursor, was recovered from Carboniferous strata in the U.S. state of Texas. The work was carried out by scientists from the Nanjing Institute of Geology and Palaeontology of the Chinese Academy of Sciences, in collaboration with colleagues from the United Kingdom, the United States, and Spain.

Although the insect already possessed the three pairs of walking legs typical of modern insects, its abdomen retained paddle-shaped lobes suited for swimming. The findings were recently published online in the journal Nature.

Cai Chenyang, a researcher at the institute who led the study, said that abdominal appendages in extant insects are largely reduced, with only the three thoracic pairs remaining. Chosha praecursor, he noted, offers a snapshot of the transition: the ancestral aquatic appendages had not yet disappeared entirely but were being gradually modified and simplified as the insect adapted to life on land.

The fossil, identified as an adult female, measures about 3.2 cm in body length, extending to nearly 5 cm with its elongated tail structure, and has a fusiform shape.

Its thorax bore three pairs of walking legs, and its ovipositor and tail already showed typical insect features. However, segments one through nine of the abdomen still carried segmented appendages, with the rear pairs flattened into paddle-like forms.(Xinhua)