Abstract
Filamentous microfossils belonging to Cephalophytarion from the 850 Ma Bitter Springs Group have previously been used as key analogues in support of a biological interpretation for filamentous objects from the 3460 Ma Apex chert. Here we provide a new perspective on this interpretation by combining Raman data with correlative electron microscopy data from both Cephalophytarion and Apex specimens. We show that, when analysed at high spatial resolution, the Apex filaments bear no morphological resemblance to the younger Bitter Springs microfossils. Cephalophytarion filaments are shown to be cylindrical, comprising chains of box-like cells of approximately constant dimensions with lateral kerogenous walls and transverse kerogenous septa. They exhibit taphonomic shrinkage and folding, possess fine cylindrical sheaths and are permineralized by sub-micrometric quartz grains. They fulfil all established biogenicity criteria for trichomic microfossils. In contrast, Apex filaments do not possess lateral cell walls, are not cylindrical in nature, and vary considerably in diameter along their length. Their kerogenous carbon does not have a cell-like distribution and their chemistry is consistent with an origin as exfoliated phyllosilicate grains. This work demonstrates the importance of high-resolution data when interpreting the microstructure, and origins, of putative Precambrian microfossils.
| Original language | English |
|---|---|
| Pages (from-to) | 1247-1260 |
| Number of pages | 14 |
| Journal | Journal of the Geological Society |
| Volume | 176 |
| Issue number | 6 |
| DOIs | |
| Publication status | Published - 1 Jan 2019 |
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Comparative multi-scale analysis of filamentous microfossils from the c. 850 ma bitter springs group and filaments from the c. 3460 ma apex chert. / Wacey, David; Eiloart, Kate; Saunders, Martin.
In: Journal of the Geological Society, Vol. 176, No. 6, 01.01.2019, p. 1247-1260.Research output: Contribution to journal › Article
TY - JOUR
T1 - Comparative multi-scale analysis of filamentous microfossils from the c. 850 ma bitter springs group and filaments from the c. 3460 ma apex chert
AU - Wacey, David
AU - Eiloart, Kate
AU - Saunders, Martin
PY - 2019/1/1
Y1 - 2019/1/1
N2 - Filamentous microfossils belonging to Cephalophytarion from the 850 Ma Bitter Springs Group have previously been used as key analogues in support of a biological interpretation for filamentous objects from the 3460 Ma Apex chert. Here we provide a new perspective on this interpretation by combining Raman data with correlative electron microscopy data from both Cephalophytarion and Apex specimens. We show that, when analysed at high spatial resolution, the Apex filaments bear no morphological resemblance to the younger Bitter Springs microfossils. Cephalophytarion filaments are shown to be cylindrical, comprising chains of box-like cells of approximately constant dimensions with lateral kerogenous walls and transverse kerogenous septa. They exhibit taphonomic shrinkage and folding, possess fine cylindrical sheaths and are permineralized by sub-micrometric quartz grains. They fulfil all established biogenicity criteria for trichomic microfossils. In contrast, Apex filaments do not possess lateral cell walls, are not cylindrical in nature, and vary considerably in diameter along their length. Their kerogenous carbon does not have a cell-like distribution and their chemistry is consistent with an origin as exfoliated phyllosilicate grains. This work demonstrates the importance of high-resolution data when interpreting the microstructure, and origins, of putative Precambrian microfossils.
AB - Filamentous microfossils belonging to Cephalophytarion from the 850 Ma Bitter Springs Group have previously been used as key analogues in support of a biological interpretation for filamentous objects from the 3460 Ma Apex chert. Here we provide a new perspective on this interpretation by combining Raman data with correlative electron microscopy data from both Cephalophytarion and Apex specimens. We show that, when analysed at high spatial resolution, the Apex filaments bear no morphological resemblance to the younger Bitter Springs microfossils. Cephalophytarion filaments are shown to be cylindrical, comprising chains of box-like cells of approximately constant dimensions with lateral kerogenous walls and transverse kerogenous septa. They exhibit taphonomic shrinkage and folding, possess fine cylindrical sheaths and are permineralized by sub-micrometric quartz grains. They fulfil all established biogenicity criteria for trichomic microfossils. In contrast, Apex filaments do not possess lateral cell walls, are not cylindrical in nature, and vary considerably in diameter along their length. Their kerogenous carbon does not have a cell-like distribution and their chemistry is consistent with an origin as exfoliated phyllosilicate grains. This work demonstrates the importance of high-resolution data when interpreting the microstructure, and origins, of putative Precambrian microfossils.
UR - http://www.scopus.com/inward/record.url?scp=85074991069&partnerID=8YFLogxK
U2 - 10.1144/jgs2019-053
DO - 10.1144/jgs2019-053
M3 - Article
VL - 176
SP - 1247
EP - 1260
JO - Journal of the Geological Society, London
JF - Journal of the Geological Society, London
SN - 0016-7649
IS - 6
ER -