Sterane molecular fossils with side-chain methylations have not been reported in the bacterial domain. One such sterane, 24-isopropylcholestane, has been attributed to ancient sponges, potentially representing the earliest evidence for animals on Earth. This study demonstrates that symbiotic bacteria are capable of producing the 24-isopropyl sterol side-chain, suggesting that bacteria should not be dismissed as sources of these biomarkers in the rock record.
- Malory O. Brown
- Babatunde O. Olagunju
- Paula V. Welander
