Reference : New insights on the paleobiology, biostratigraphy and paleogeography of the pre-Sturt...
Scientific journals : Article
Physical, chemical, mathematical & earth Sciences : Earth sciences & physical geography
http://hdl.handle.net/2268/238833
New insights on the paleobiology, biostratigraphy and paleogeography of the pre-Sturtian microfossil index taxon Cerebrosphaera
English
Cornet, Yohan mailto [Université de Liège - ULiège > > > Doct. sc. (géologie - Bologne)]
François, Camille mailto [> >]
Compère, Philippe mailto [Université de Liège - ULiège > Département de Biologie, Ecologie et Evolution > Morphologie fonctionnelle et évolutive >]
Callec, Yves [> >]
Roberty, Stéphane mailto [Université de Liège - ULiège > Département de Biologie, Ecologie et Evolution > Ecophysiologie et physiologie animale >]
Plumier, Jean-Christophe mailto [Université de Liège - ULiège > Département de Biologie, Ecologie et Evolution > Ecophysiologie et physiologie animale >]
Javaux, Emmanuelle mailto [Université de Liège - ULiège > Département de géologie > Early Life Traces & Evolution-Astrobiology >]
Sep-2019
Precambrian Research
Elsevier
Yes (verified by ORBi)
International
0301-9268
Netherlands
[en] Neoproterozoic ; Cerebrosphaera ; Wall ultrastructure ; Microspectroscopy ; Eukaryotes ; Biostratigraphy
[en] Important biological and geological events occurred during the early Neoproterozoic. Among diversifying eukaryotic assemblages, populations of the distinctive robust organic-walled vesicular microfossils (acritarchs) Cerebrosphaera occur as a short-lived taxon in several late Tonian to early Cryogenian worldwide successions. Here we report the first occurrence of this taxon in the Bouenza Subgroup (Republic of the Congo), enlarging its paleogeographic distribution and biostratigraphic significance. We also attempt to determine its biological affinities, using a combined analytical approach on specimens from the Kanpa and Hussar Formations, Australia, and from the Svanbergfjellet Formation, Spitsbergen. Morphological and quantitative analyses were performed using light microscopy and scanning electron microscopy, on more than 200 specimens and 9 specimens, respectively. The analyses show fine-scale morphological details and a morphological continuum between the former species Cerebrosphaera ananguae and Cerebrosphaera buickii, confirming their synonymy as proposed by a recently revised taxonomy. These observations also highlighted the presence of a previously mentioned envelope, formerly described and illustrated here for the first time. Ultrastructural analyses performed with TEM revealed two types of complex (bilayered and trilayered) wall ultrastructures. The molecular structure and thermal maturity of the organic walls estimated using Infrared and Raman microspectroscopies, reveal the highly aromatic composition of Cerebrosphaera’s wall biopolymer with short/highly branched aliphatic chains unlike known biopolymers. The complex morphology, ultrastructure and recalcitrant chemistry, combined with the large size of Cerebrosphaera confirm its eukaryotic nature. Comparison with possible modern analogues permits to suggest an affinity to stem metazoan eggs. This hypothesis is consistent with estimates from molecular clocks and, if confirmed, would provide an older evidence for stem metazoans than the Cryogenian biomarker and Ediacaran body fossil records. Our study reveals that Cerebrosphaera populations are important for the late Proterozoic biostratigraphy, but also participated to the Neoproterozoic diversification eukaryotes in connected oceans.
Astrobiology
CER - Conseil Européen de la Recherche ; BELSPO - SPP Politique scientifique - Service Public Fédéral de Programmation Politique scientifique ; F.R.S.-FNRS - Fonds de la Recherche Scientifique
Researchers ; Professionals ; Students
http://hdl.handle.net/2268/238833
10.1016/j.precamres.2019.105410
https://www.sciencedirect.com/science/article/pii/S030192681830634X?via%3Dihub
FP7 ; 308074 - ELITE - Early Life Traces, Evolution, and Implications for Astrobiology

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