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preserved in the gypsum crystals of one
complete cycle (6(th) cycle at Monte Tondo
quarry) showed abundant, regularly arranged
filamentous forms that resemble
morphologically modern obligate
phototrophes, cyanobacteria colonizing
modern photic. shallow-water gypsum basins.
At least four different bacterial populations
have been recognized:
a) filamentous type cyanobacteria with
characteristic inserted funnel shaped structure
resembling the modern Scytonematacean;
b) Type 1 organisms consisting of filamentous
structures impregnated by clay minerals
containing pyrite grains in the outer sheath;
c) Type 2 filaments filled by C lay minerals
with dolomite in the Outer sheath;
d) Type 3 filamentous organisms with a
central hollow tube and an encrusted outer
sheath mainly composed of calcium carbonate.
These organisms were probably associated
with other heterotrophic bacteria as suggested
by the presence of dolomite and pyrite
structures. The size and preservation suggest
that most of these cyanobacteria were likely
conducting oxygenic photosynthesis as
presently observed in modern solar salt works.
It follows that they were living in shallow
water settings or settled down from the water
column to the bottom of a relatively deep
evaporite basin.
2009020061
真 核 生 物 化 石 保 存 的 实 验 证 据 : 二 氧 化 硅
溶 液 中 的 洋 葱 表 皮 细 胞 = Experimental
evidence for eukaryotic fossil preservation:
Onion skin cells in silica solution. ( 英 文 ).
Chen Xiaozheng; Wang Wei; Shang Qinghua;
Lou Yue; Liu Xinchun; Cao Changqun; Wang
Yue. Precambrian Research, 2009, 170(3-4):
223-230
Research on the origin of eukaryotes often
focuses on the exceptional preservation found
in silicified Precambrian fossils. Nuclei like
subcellular structures in well-preserved fossil
becomes confusion and arguments, which
focus on whether the partial degradation of
prokaryotes produces artifacts that resemble a
‘ nucleus ’ , or fossilized nuclei of
eukaryotes. In order to understand the
mechanisms of silicification and identify the
fossilized subcellular and microstructures in
rocks, a series of laboratory controlled
experiments were performed for simulating
the silicification process. The effects of
different silica solutions in eukaryote
fossilization were studied in our experiments
by exposing onion skin cells (epidermis) to
silica solutions. Onion skin provides a good
experimental model because of its well
characterized cellular structures which are
easily observed. The designed experiments
revealed that the possibility of onion cell
preserved as a “ fossil ” with nuclear
structures, the first week fossilization, or
mineralization as rapid as 1 week is important.
And the experiment also revealed interactions
between silica and the onion skin cell wall
surface functional groups were weak. The
preservation of nuclei in the onion skin model
was due to precipitation in highly
supersaturated silica solutions rather than
simply the high silica concentration. When the
silica gel precipitates slowly at low
supersaturation states, the nuclei were not well
preserved, but the rapid precipitation at high
supersaturated silica conditions preserved
nuclear structures. A better understanding of
the processes involved in onion skin
fossilization will further contribute to issues
concerning the silicification of other
eukaryotic materials.
2009020062
俄 罗 斯 奥 列 尼 奥 克 隆 起 里 菲 期 Arymas 组
和 Debengda 组 微 化 石 : 时 代 和 特 征 研 究
= Microfossils from the Arymas and
Debengda formations, the Riphean of the
Olenek Uplift: Age and presumable nature.
( 英 文 ). Stanevich A M; Maksimova E N;
Kornilova T A; Gladkochub D P;
Mazukabzov A M; Donskaya T V.
Stratigraphy and Geological
Correlation, 2009, 17(1): 20-35
Studied assemblages of diverse organicwalled
microfossils separated from the
Arymas and Debengda formations of the
Olenek Uplift include several paleobiological
groups of microorganisms. Sufficiently large
morphotypes of the first group are identified
with remains of cyanobacteria. Morphotypes
of variable spiral structure, which dwelt in
association or in symbiosis with cyanobionts,
are attributed to the same bacterial community.
The other group includes a series of different
acritarch genera whose characters suggest
their affinity with green algae of the order
Desmidiales. It is very likely that this group
coexisted on siliciclastic shoals with large
ancestral forms of the present-day brown
algae. Several microfossil taxa have been
known before from the Neoproterozoic
deposits only. With due regard for the
relatively gradual accumulation of
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