Bisnorgammacerane traces predatory pressure and the persistent rise of algal ecosystems after Snowball Earth.

ABSTRACT: Eukaryotic algae rose to ecological relevance after the Neoproterozoic Snowball Earth glaciations, but the causes for this consequential evolutionary transition remain enigmatic. Cap carbonates were globally deposited directly after these glaciations, but they are usually organic barren or thermally overprinted. Here we show that uniquely-preserved cap dolostones of the Araras Group contain exceptional abundances of a newly identified biomarker: 25,28-bisnorgammacerane. Its secular occurrence, carbon isotope systematics and co-occurrence with other demethylated terpenoids suggest a mechanistic connection to extensive microbial degradation of ciliate-derived biomass in bacterially dominated ecosystems. Declining 25,28-bisnorgammacerane concentrations, and a parallel rise of steranes over ho

SUBMITTER: van Maldegem LM 

PROVIDER: S-EPMC6351664 | biostudies-literature | 2019 Jan

REPOSITORIES: biostudies-literature