Analysis of Mesoproterozoic sediment extracts from the North China Craton by gas chromatography–mass spectrometry metastable reaction monitoring revealed an extended series of C₁₈–C₃₃ 13α(n-alkyl)-tricyclic terpanes. This discovery extends the previous known series to C₃₃ with sixteen homologs. Because of the abundant presence of C₂₂ and C₂₇ homologs, and no isomeric peaks for the homologs > C₂₄, it was confirmed that the side chain at the C-13 position is a long-chain n-alkyl group without a methyl substituent or an asymmetric carbon atom. The distribution of the extended tricyclic terpanes in the Mesoproterozoic sediments is mainly controlled by a primitive biological community, probably from certain specific bacteria and/or cyanobacteria. Their biological precursor was probably inhibited by high-salinity water conditions and not evolved during the deposition of the Gaoyuzhuang Formation.