Fossil cyanobacteria

1
diatom
Dinoflagellate cyst
Prasinophyte phycoma
Fossil cyanobacteria
2
Fossil Preservation
Not all organisms make easily preserved
parts Even silica and carbonate shells can
dissolve Not all parts are specific to certain
taxa Environmental conditions can
influence Variations in species evolution can
make interpretation difficult Older fossils can
be hard to identify as such Can also be altered
by temperature and geologic processes
3
Coccoid cyanobacteria can be thermally altered to
look like filamentous fossils due to
kerogenization of mucus envelopes rather than
individual cells
440 Mya Kazmierczak and Kramer, 2002
4
2-methyl bacteriohopanepolyols characteristic of
cyanobacteria
Summons et al., 1999
1.6 Gyr Barney Creek Formation Brocks et al., 2005

• Trimethylarylisoprenoids -gt carotenoid breakdown
  products
• o Carotenoid okenane -gtpurple sulfur bacteria
  (lt20m)
• i, c carotenoids -gt planktonic green and brown
  anerobic phototrophs

5
Schopf 1993
6
Fossil structures part of larger forms that
extend in 3 dimensions changing focal depth can
show additional structures