Australasian Science: Australia's authority on science since 1938

Cholesterol Fossil Found

By Stephen Luntz

Cholesterol and other sterols have been obtained from a 380 million-year-old fossil in Gogo Devonian deposits in the West Kimberley. The discovery nearly triples the age of the oldest discovery of these important molecules.

“The exceptional preservation of the crab-like fossil, which has extended the occurrence of sterols by 250 million years, is a consequence of early microbial encapsulation preventing full decomposition in the Devonian seas,” says PhD student Ines Melendez of Curtin University’s Western Australian Organic and Isotope Geochemistry Centre (WA-OIGC). The discovery was published in Nature Scientific Reports.

Ancient sterols usually have an alcohol group added to them over time, Melendez says, so cholesterol becomes cholestane. However, in this case it is thought an adaptive microbial community rapidly encapsulated part of the fossil, sealing it off from further damage.

This would only have occurred in an environment without oxygen but with an active microbial population. She thinks the crustacean was living on a reef, and when it died it fell into deep anoxic waters.

Modern crabs are high in LDL, or “bad cholesterol”, and Melendez says the quantity identified in this creature indicates it must have been a common molecule then as well.

“This opens up a novel window of opportunity to study such components in very ancient samples, and improves our understanding of microbial evolution and past environmental conditions,” says WA-OIGC director Prof Kliti Grice.

The cholesterol in this crab-like creature has survived intact for 380 million years.