Morphological and ecological complexity in early eukaryotic ecosystems

  title={Morphological and ecological complexity in early eukaryotic ecosystems},
  author={Emmanuelle J Javaux and Andrew H. Knoll and Malcolm R. Walter},
Molecular phylogeny and biogeochemistry indicate that eukaryotes differentiated early in Earth history. Sequence comparisons of small-subunit ribosomal RNA genes suggest a deep evolutionary divergence of Eukarya and Archaea; C27–C29 steranes (derived from sterols synthesized by eukaryotes) and strong depletion of 13C (a biogeochemical signature of methanogenic Archaea) in 2,700 Myr old kerogens independently place a minimum age on this split. Steranes, large spheroidal microfossils, and rare… 
Paleobiological perspectives on early eukaryotic evolution.
  • A. Knoll
  • Geography, Biology
    Cold Spring Harbor perspectives in biology
  • 2014
Protists continued to diversify along with animals in the more pervasively oxygenated oceans of the Phanerozoic Eon, and the Mid-Neoproterozoic establishment or expansion of eukaryophagy provides a possible mechanism for accelerating eUKaryotic diversification long after the origin of the domain.
TEM evidence for eukaryotic diversity in mid‐Proterozoic oceans
Biomarker molecular fossils in 2770 Ma shales suggest that the Eucarya diverged from other principal domains early in Earth history. Nonetheless, at present, the oldest fossils that can be assigned
The early eukaryotic fossil record.
  • E. Javaux
  • Geography, Environmental Science
    Advances in experimental medicine and biology
  • 2007
The record of biological innovations documented by the fossils shows that eukaryotes had evolved most cytological and molecular complexities very early in the Proterozoic but environmental conditions delayed their diversification within clades until oxygen level and predation pressure increased significantly.
Estimating the timing of early eukaryotic diversification with multigene molecular clocks
Taxon-rich multigene data combined with diverse fossils and a relaxed molecular clock framework are used to estimate the timing of the last common ancestor of extant eukaryotes and the divergence of major clades, suggesting that long stems preceded diversification in the major eUKaryotic lineages.
Written in Stone: The Fossil Record of Early Eukaryotes
The early evolutionary history of the eukaryotes, as revealed by the Neoarchean–Proterozoic fossil record, can be described in three stages, which are broadly consistent with predictions from the molecular phylogeny of eUKaryotes.
A suite of taxonomically resolved body fossils and biomarkers, together with estimates of acritarch and compression fossil diversity, suggest that while divergences among major eukaryotic clades or ‘super-groups’ may have occurred as early as latest Paleoproterozoic through MesoproTerozoic time, the main phase of eUKaryotic diversification took place several hundred million years later, during the middle Neoproverozoic Era.
Early Cell Evolution, Eukaryotes, Anoxia, Sulfide, Oxygen, Fungi First (?), and a Tree of Genomes Revisited
New views of eukaryote phylogeny suggest that fungi may be among the earliest‐branching eUKaryotes, and from the standpoint of the fungal feeding habit (osmotrophy rather than phagotrophy) and the diversity in their ATP‐producing pathways, a eucaryotic tree with fungi first would make sense.
Absence of biomarker evidence for early eukaryotic life from the Mesoproterozoic Roper Group: Searching across a marine redox gradient in mid‐Proterozoic habitability
One of the first integrated investigations of Mesoproterozoic biomarker records performed in parallel with established inorganic redox proxy indicators reveals a temporally variable paleoredox structure through the Velkerri Formation as gauged from iron mineral speciation and trace-metal geochemistry, vacillating between oxic and anoxic.


Towards a natural system of organisms: proposal for the domains Archaea, Bacteria, and Eucarya.
It is proposed that a formal system of organisms be established in which above the level of kingdom there exists a new taxon called a "domain." Life on this planet would be seen as comprising three domains, the Bacteria, the Archaea, and the Eucarya, each containing two or more kingdoms.
Megascopic eukaryotic algae from the 2.1-billion-year-old negaunee iron-formation, Michigan.
Hundreds of specimens of spirally coiled, megascopic, carbonaceous fossils resembling Grypania spiralis (Walcott), have been found in the 2.1-billion-year-old Negaunee Iron-Formation at the Empire Mine, near Marquette, Michigan, placing the origin of organelle-bearing eukaryotic cells prior to 2.
A new model for Proterozoic ocean chemistry
There was a significant oxidation of the Earth's surface around 2 billion years ago (2 Gyr). Direct evidence for this oxidation comes, mostly, from geological records of the redox-sensitive elements