Transcript Document

diatom
Dinoflagellate cyst
Prasinophyte phycoma
Fossil cyanobacteria
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
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
2-methyl
bacteriohopanepolyols
characteristic of
cyanobacteria
Summons et al., 1999

Trimethylarylisoprenoids > carotenoid breakdown
products
o Carotenoid okenane >purple sulfur bacteria
(<20m)
i, c carotenoids -> planktonic
green and brown anerobic
phototrophs
1.6 Gyr Barney Creek
Formation Brocks et al.,
2005
Anabena sp.
Spirulina sp.
Schopf 1993
‘Fossil’ structures part of larger forms that extend in 3
dimensions
changing focal depth can show additional structures