Perri, E. and Tucker, M. E. (2007) 'Bacterial fossils and
microbial dolomite in Triassic stromatolites.', Geology., 35
(3). pp. 207-210. Triassic stromatolitic dolomite from Italy
preserves mineralized bacterial remains, one of the first
unequivocal identifications of such structures in the geological
record. They consist of empty spheroids 1.0 µm diameter
resembling coccoid bacteria, and smaller, 150–400 nm, objects
interpreted as dwarf bacterial forms, occurring within and
between syn-sedimentary dolomite crystals. Moreover, gently
folded sheets, 100–200 nm thick and several micrometers long,
form a sub-polygonal network reminiscent of EPS (extracellular
polymeric substance). Their granular-textured surfaces suggest
bacterial degradation of original organic matter. These features
confirm a biological origin for the stromatolites, as in modern
microbial mats, and the preserved original geochemical
signatures indicate early precipitation of Mg-carbonates induced
through microbial sulfate-reducing metabolic ac