Authors
Zhenfei Wang, Yongbo Peng, Qing Tang, James D Schiffbauer, Shuhai Xiao, David A Fike, Zice Jia, Dong Feng, Peter W Crockford, Yaoping Cai, Xunlai Yuan, Lisa M Pratt
Published in
Proceedings of the National Academy of Sciences of the United States of America. Volume 123. Issue 35. Pages e2526201123. Epub Aug 24, 2026.
Abstract
Chemosymbiosis may have been a key driver of early animal evolution and diversification. Yet evidence for animal-microbe nutritional partnerships in the fossil record of early metazoans remains scarce, largely owing to the limited availability of robust geochemical proxies and suitable fossilization pathways. Here, we report extremely low molybdenum isotope (δ98Mo) values in pyritized fossils of the terminal Ediacaran Conotubus, a nonbiomineralized cloudinomorph representing some of the earliest metazoans. Such low δ98Mo values are otherwise only known in modern cold-seep chemosymbiotic tubeworms hosting sulfur-oxidizing bacterial symbionts. Homogeneously low δ34S signatures of fossils indicate that rapid pyritization in early diagenesis under euxinic taphonomic settings preserved primary Conotubus chitinous δ98Mo. Substantial δ34S fractionation relative to seawater sulfate and high Δ33S values indicate that active microbial H2S oxidation occurred within their habitat. Our findings provide evidence that Conotubus may have engaged in chemosymbiosis with sulfur-oxidizing bacteria-the earliest geochemically supported case in the fossil record. This trophic strategy likely enabled Conotubus to thrive in the redox-stratified Ediacaran ocean where sulfide and oxidants coexisted, facilitating its ecological success.
PMID:
42636363
Bibliographic data and abstract were imported from PubMed on 25 Aug 2026.
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