Amphibious Stem-Insect Reveals Early History of Insect Terrestrialization

Excerpt (and research article link):

The formation of complex terrestrial ecosystems was a significant innovation in the evolutionary history of life on Earth. This event signified the expansion of life beyond marine environments and marked the beginning of a new phase in the diversification of terrestrial biota. As the most species-rich animal group on our planet, insects played an important role in this evolutionary transition to land. However, significant gaps in the relevant research have long existed. 

Now, an international research team has discovered a new stem-group insect from the Late Mississippian period, approximately 324 million years ago. They combined this discovery with previously enigmatic fossil material to reconstruct a pivotal stage in the early evolution of insects. The fossils suggest that insects did not immediately become fully terrestrial after colonizing land. Instead, they retained and remodeled ancestral aquatic features and passed through a prolonged semi-aquatic, amphibious phase.

The study was led by Prof. CAI Chenyang from the Nanjing Institute of Geology and Palaeontology of the Chinese Academy of Sciences (NIGPAS) and Erik Tihelka, a joint-training Ph.D. student at the University of Cambridge, who collaborated with researchers from the United States, Spain, and other countries. 

The findings were published in Natureon August 26.

This study describes a new species, Chosha praecursor. The researchers also investigated enigmatic stem‑insect material from the Early Devonian chert biota of Britain and the Late Carboniferous Mazon Creek biota of the United States.

These insect fossils fill critical gaps in early insect evolution. The fossils also revise long-standing interpretations of insect body-plan transformation and pancrustacean terrestrialization. Furthermore, they furnish key empirical evidence for the gradual aquatic-to-terrestrial evolutionary transition of insects.