Two novel isomeric decamethylhenicosanes (C31 hydrocarbons) were newly identified as a new biomarker class for B. brawnii in Liao et al. (2018).
These hydrocarbons have additional methyl groups on the isoprenoid chains.
It seems to be unstable especially for C-C bonds between 2-3, 6-7, 15-16, and 19-20.
Therefore it would not be preserved in thermally matured rocks, but it would be compounds of interest for immatured samples.
Liao et al. (2018) “Two novel decamethyl henicosanes (C31H64) identified in a Maoming Basin shale, China”