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Raman spectroscopy and microstructural comparison of carbonaceous compression and body fossils from the Neoproterozoic of Siberian and Eastern European platforms
Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleobiologi. (ORIGINS AND EARLY DIVERSIFICATION OF PHOTOSYNTHETIC MICROBIOTA)
Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Paleobiologi. (ORIGINS AND EARLY DIVERSIFICATION OF PHOTOSYNTHETIC MICROBIOTA)
(Engelska)Manuskript (preprint) (Övrigt vetenskapligt)
Abstract [en]

Macroscopic, organic-walled fossils preserved as carbonaceous compressions and body fossils are commonly occurring in the Neoproterozoic-Cambrian successions worldwide. Most of these fossils, including studied here Chuaria, Tawuia, and Beltemelliformis, have been accepted as algae, and Sabellidites as an early metazoan. They possess limited characters for biological identification and differ in gross morphology of spherodial vs. tubular millimetre-sized specimens. Consequently, other methods than morphologic observations are needed to elucidate their affinities and, ultimately, phylogeny. Here we present a comparison of the Raman spectrographic signatures and new scanning electron microscope (SEM) observations on different carbonaceous compression and body fossils from the Khajpakh Formation (Siberian Platform), and Nekrasovo Formation (East European Platform), referred to the Tonian-Cryogenian transitional interval (c. 840-700 Ma) and the lowermost Cambrian stage, respectively. Data from the Raman spectroscopy of the walls of non-mineralised organisms reveal their chemical properties, and, in additions to microstructural characters, may be used to resolve the fossils’ phylogenetic affinities. To test the basic recognition of organic matter in studied photosynthetic organisms vs. animals, we have examined algal compression fossils and organically-preserved body-fossil. Differences in the Raman spectroscopic signature between various taxa have been observed. Vibrational absorption bands similar to those characteristic of α-chitin signature have been detected in the organic wall of Sabellidites, consistent with its metazoan identity. Distinct organic matter spectra of the macroalgae Chuaria, Tawuia and Beltanelliformis, and the possible early annelid Sabellidites indicate that Raman spectroscopy could be a useful method in identifying different branches of the early eukaryotes. Additionally, the recognition of the earliest metazoans among un-diagnostic tubular fossils by biochemical signatures and wall ultrastructure, could provide the minimum age of their origins.

Nyckelord [en]
Neoproterozoic, Cambrian, tubular fossils, organic body fossils, Raman spectroscopy, SEM, East European Platform, Siberian Platform
Nationell ämneskategori
Naturvetenskap Geologi
Forskningsämne
Geovetenskap med inriktning mot historisk geologi och paleontologi
Identifikatorer
URN: urn:nbn:se:uu:diva-265206OAI: oai:DiVA.org:uu-265206DiVA, id: diva2:864103
Projekt
Palaeobiology and diversification of Proterozoic-Cambrian photosynthetic eukaryotes
Forskningsfinansiär
Vetenskapsrådet, 621-2012-1669Tillgänglig från: 2015-10-25 Skapad: 2015-10-25 Senast uppdaterad: 2015-12-04
Ingår i avhandling
1. Palaeobiology and diversification of Proterozoic-Cambrian photosynthetic eukaryotes
Öppna denna publikation i ny flik eller fönster >>Palaeobiology and diversification of Proterozoic-Cambrian photosynthetic eukaryotes
2015 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

One of the most important events in the history of life is the evolution of the complex, eukaryotic cell. The eukaryotes are complex organisms with membrane-bound intracellular structures, and they include a variety of both single-celled and multicellular organisms: plants, animals, fungi and various protists. The evolutionary origin of this group may be studied by direct evidence of past life: fossils. The oldest traces of eukaryotes have appeared by 2.4 billion years ago (Ga), and have additionally diversified in the period around 1.8 Ga. The Mesoproterozoic Era (1.6-1 Ga) is characterised by the first evidence of the appearance complex unicellular microfossils, as well as innovative morphologies, and the evolution of sexual reproduction and multicellularity. For a better understanding of the early eukaryotic evolution and diversification patterns, a part of this thesis has focused on the microfossil records from various time periods and geographic locations. Examination of microfossil morphology, cell wall microstructure and biochemical properties, reflect their intracellular complexity and function, and allow reconstructions of their life cycle, as well as observing the evolutionary pattern of change from Mesoproterozoic, to Cambrian-Ordovician transition. Several case studies included assemblages deriving from Mesoproterozoic, Neoproterozoic and early Paleozoic time intervals that show disparate morphotypes and innovative features indicative of algal clades. The Mesoproterozoic Ruyang Group in northern China has yielded a diverse microfossil assemblage that provides important clues about the diversification of different eukaryotic groups. Furthermore these microfossils contributed an additional evidence for the emergence of the crown group Eukarya by 1.7-1.4 Ga. In another part of this thesis, examination of wall microstructure and chemical properties via Raman spectroscopy has been used to assess the biological affinities of various Neoproterozoic problematic carbonaceous compression fossils. Studies on the early Phanerozoic (c. 545-485 Ma) assemblages from Estonia reconstructed patterns of the early radiations of phytoplankton and its evolutionary innovations. A continuing theme in this thesis has been using a combination of evidence of microfossils’ fine-scale morphology, ecology and chemical properties to determine their function in life, in addition to their systematic position.

Ort, förlag, år, upplaga, sidor
Uppsala: Acta Universitatis Upsaliensis, 2015. s. 47
Serie
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1308
Nyckelord
microfossils, eukaryotes, Mesoproterozoic, Neoproterozoic, Cambrian, Ordovician, palaeobiology, biostratigraphy, phylogeny, China, Estonia, Siberian Platform, prasinophytes, microstructure, Raman spectroscopy
Nationell ämneskategori
Geologi
Forskningsämne
Geovetenskap med inriktning mot historisk geologi och paleontologi
Identifikatorer
urn:nbn:se:uu:diva-265229 (URN)978-91-554-9389-9 (ISBN)
Disputation
2015-12-11, Hambergsalen, Geocentrum, Villavägen 16, 752 36, Uppsala, 10:15 (Engelska)
Opponent
Handledare
Projekt
Palaeobiology and diversification of Proterozoic-Cambrian photosynthetic eukaryotes
Forskningsfinansiär
Vetenskapsrådet, 621-2009-4445
Tillgänglig från: 2015-11-19 Skapad: 2015-10-26 Senast uppdaterad: 2016-01-13

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