An international research team led by scientists from the Nanjing Institute of Geology and Palaeontology of the Chinese Academy of Sciences has reported the discovery of an early insect species that provides new insights into the evolutionary transition from aquatic to terrestrial life. The fossil, named Chosha praeursor, dates back approximately 324 million years to the Carboniferous period and was found in Texas, United States.

The specimen, identified as an adult female, measures about 3.2 centimeters in body length, extending to nearly 5 centimeters including its elongated tail. It exhibits a combination of anatomical features that reflect both aquatic and terrestrial adaptations. While it had the three pairs of walking legs characteristic of modern insects, the abdomen retained paddle-shaped lobes, indicating it was still adapted for swimming.

Researchers highlight that in contemporary insects, abdominal appendages are mostly reduced, with only three pairs of legs on the thorax remaining. Chosha praeursor offers a rare glimpse into this evolutionary process, as its ancestral aquatic appendages had not yet disappeared but were in the process of modification and simplification in response to life on land.

The fossil was recovered from shallow-water deltaic deposits near shorelines, suggesting that the insect inhabited humid transitional environments between land and water. This semi-aquatic habitat likely provided the adaptive pressures driving the gradual development of terrestrial features such as improved walking legs and respiratory structures necessary for life outside water.

According to study lead Cai Chenyang, the discovery represents an important evolutionary link illustrating how early insects evolved new body structures to thrive on land about 320 million years ago. The findings were published recently in the journal Nature and shed light on the morphological changes involved in one of the key transitions in the history of terrestrial life.