2026-08-25 中国科学院（CAS）
The stem-group insect Chosha praecursor Tihelka, Engel & Cai, 2026 from the Carboniferous Tesnus Formation (ca. 324 Ma), Texas, USA. (Image by NIGPAS)
＜関連情報＞
- https://english.cas.cn/newsroom/headlines/202608/t20260826_1188824.shtml
- https://www.nature.com/articles/s41586-026-10961-2
両生類の幹昆虫が陸上への移住に光を当てる Amphibious stem-insect sheds light on colonization of land
Erik Tihelka,Carlos Vásquez,Michael S. Engel,Frederick R. Schram,Jesus Lozano-Fernandez & Chenyang Cai
Nature Published:26 August 2026
DOI:https://doi.org/10.1038/s41586-026-10961-2
Abstract
Molecular clock analyses1,2,3, trace fossils4, exceptionally preserved amphibious stem-myriapods5 and sea scorpions6 have recently challenged classical assumptions about the timeline of the animal colonization of land7, suggesting that terrestrial ecosystems may date back as far as the Cambrian period. However, the early evolutionary history of the most successful clade of animals, the insects, has remained elusive, as the period of their early diversification constrained by time divergence estimates falls within the notorious ‘hexapod gap’ in the fossil record8. Here we describe Chosha praecursor gen. et sp. nov. from the Carboniferous period (Late Mississippian epoch, approximately 324 million years ago) Tesnus Formation in Texas. Cross-polarized light imaging reveals that C. praecursor possesses insect apomorphies including an ovipositor and a terminal filament but differs from crown-group insects, most notably with respect to the presence of multisegmented abdominal legs with paddle-like modifications. Our phylogenetic reconstruction recovers C. praecursor as a hexapod, strongly favouring its placement as an early-diverging insect. A revision of three other enigmatic hexapod fossils, the Devonian period Leverhulmia and two undescribed Carboniferous fossils from the Mazon Creek Lagerstätte, demonstrates diverse body organization in Palaeozoic wingless insects. Together, these stem-group fossils represent the earliest uncontested insects and partly reconcile the incongruence between molecular clock estimates and the fossil record. The unusual abdominal gill-like appendages of Chosha suggest a semiaquatic mode of life in at least some stem-insects and revise our understanding of the assembly of insect morphological organization.
