sentence: Methylated heptadecanes have been recovered from a variety of environments including freshwater microbial mats of calcifying cyanobacteria ( Thiel et al ., 1997 ) , hot spring cyanobacterial mats ( Shiea et al ., 1990 ) , microbial carbonates ( Arp et al ., 1999 ) , carbonate samples from the Late Jurassic ( Hefter et al ., 1993 ) and stromatolitic carbonate rocks that have been inhabited by cyanobacteria since the Cenozoic Eon ( Hoshino and George , 2015 ) .