The Gunflint Chert - Fossil Ecosystems of North America: A Guide to the Sites and their Extraordinary Biotas - page 13

Doushantuo Formation,
southern China
Discovered in the 1980s by Zhang Yun
of Beijing University, are beautiful
microfossils preserved in cherts and shales
which outcrop in the Yangtze Gorge of
Guizhou Province, southern China. These
rocks are only c.600 million years old, and
were deposited a mere 80 million years
before those of the Burgess Shale
(Chapter 3). They include a wealth of
eukaryotic fossils including red algae (the
corallines), plus an amazing fauna
discovered in 1995 of tiny spheres, 500
microns in diameter, which exhibit cell
division into pairs, quartets, octads, and so
on, and have been interpreted as the eggs
and embryos of animals - the 'Cambrian
Explosion' was yet to happen, but animal
evolution had at last begun.

their basal cells differentiated into
holdfasts attached to the substrate
(Butterfield et al ., 1990).

Spitsbergen
Younger still, the 700-800 million year
old chert nodules of the Draken
Conglomerate Formation (Akademi-
kerbreen Group) of northeastern
Spitsbergen contain a diverse microbiota
of over 40 taxa from a tidal flat/lagoon
complex associated with stratiform
stromatolites. Many of the microfossils
compare very closely to modern
day cyanobacteria (e.g., Polybessurus
bipartitus ), but preserved with them are
some larger (>100 microns) vase-shaped
forms and others studded with spines;
these constitute the first really diverse
biota of eukaryotes (Knoll et al ., 1991).

F URTHER R EADING
Awramik, S. M. and Barghoorn, E. S.
1977. The Gunflint microbiota.
Precambrian Research 5 , 121-142.
Barghoorn, E. S. and Tyler, S. M. 1965.
Microfossils from the Gunflint chert.
Science 147 , 563-577.
Brasier, M. D., Green, O. R. and Jephcoat,
A. P. et al . 2002. Questioning the
evidence for Earth's oldest fossils.
Nature 416 , 76-81.
Butterfield, N. J., Knoll, A. H. and
Swett, K. 1990. A bangiophyte red alga
from the Proterozoic of Arctic
Canada. Science 250 , 104-107.
Cloud, P. 1965. The significance of the
Gunflint (Precambrian microflora).
Science 148 , 27-35.
Goodwin, A. M. 1956. Facies relations in
the Gunflint Iron Formation.
Economic Geology 51 , 565-595.

Knoll, A. H. 2003. Life on a Young Planet .
Princeton University Press, Princeton.
Knoll, A. H. and Barghoorn, E. S. 1975.
A Gunflint-type flora from the Duck
Creek Dolomite, Western Australia.
Abstracts of the College Park,
Maryland, Colloquia on Chemical
evolution of the Precambrian , p. 61.
Knoll, A. H., Barghoorn, E. S. and
Awramik, S. M. 1978. New
microorganisms from the Aphebian
Gunflint Iron Formation, Ontario.
Journal of Paleontology 52 , 976-992.
Knoll, A. H., Swett, K. and Mark, J. 1991.
Paleobiology of a Neoproterozoic tidal
flat/lagoon complex: the Draken
Conglomerate Formation,
Spitsbergen. Journal of Paleontology 65 ,
531-570.