TEM evidence for eukaryotic diversity in mid‐Proterozoic oceans

  title={TEM evidence for eukaryotic diversity in mid‐Proterozoic oceans},
  author={Emmanuelle J Javaux and Andrew H. Knoll and Malcolm R. Walter},
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 to an extant eukaryotic clade are filamentous red algae preserved in ca. 1200 Ma cherts from Arctic Canada. Between these records lies a rich assortment of potentially protistan microfossils. Combined light microscopy, scanning electron microscopy, and transmission electron microscopy on 1500‐1400 Ma… 

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.

Eukaryotic organisms in Proterozoic oceans

Focus on character evolution permits inferences about the innovations in cell biology and development that underpin the taxonomic and morphological diversification of eukaryotic organisms.

Micropaleontology of the lower Mesoproterozoic Roper Group, Australia, and implications for early eukaryotic evolution

Roper fossils provide direct or inferential evidence for many basic features of eukaryotic biology, including a dynamic cytoskeleton and membrane system that enabled cells to change shape, life cycles that include resting cysts coated by decay-resistant biopolymers, reproduction by budding and binary division, osmotrophy, and simple multicellularity.

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.

Shale-hosted biota from the Dismal Lakes Group in Arctic Canada supports an early Mesoproterozoic diversification of eukaryotes

Abstract. The Mesoproterozoic is an important era for the development of eukaryotic organisms in oceans. The earliest unambiguous eukaryotic microfossils are reported in late Paleoproterozoic shales

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.

Wall ultrastructure of an Ediacaran acritarch from the Officer Basin, Australia

Well-preserved organic-walled microfossils referred to as acritarchs occur abundantly in Ediacaran deposits in the Officer Basin in Australia and a set of features suggests closer relationship to green algae than dinoflagellates.



Proterozoic and early Cambrian protists: evidence for accelerating evolutionary tempo.

  • A. Knoll
  • Geology
    Proceedings of the National Academy of Sciences of the United States of America
  • 1994
Evidently, the Cambrian diversification of animals strongly influenced evolutionary rates, within clades already present in marine communities, implying an important role for ecology in fueling a Cambrian explosion that extends across kingdoms.

Archean molecular fossils and the early rise of eukaryotes.

The presence of steranes, particularly cholestane and its 28- to 30-carbon analogs, provides persuasive evidence for the existence of eukaryotes 500 million to 1 billion years before the extant fossil record indicates that the lineage arose.

Recognizing and Interpreting the Fossils of Early Eukaryotes

Recognition of eukaryotic fossils in Proterozoic rocks is key to the integration of geological and comparative biological perspectives on protistan evolution.

Morphological and ecological complexity in early eukaryotic ecosystems

It is shown that the cytoskeletal and ecological prerequisites for eukaryotic diversification were already established in eukARYotic microorganisms fossilized nearly 1,500 Myr ago in shales of the early Mesoproterozoic Roper Group in northern Australia.


Abstract Carbonaceous compression fossils in shales of the uppermost Doushantuo Formation (ca. 555–590 Ma) at Miaohe in the Yangtze Gorges area provide a rare Burgess-Shale-type taphonomic window on

Paleobiology of the Neoproterozoic Svanbergfjellet Formation, Spitsbergen

A review of Proterozoic multicellular organisms reveals that a coenocytic grade of organization was common among early metaphytes and supports the view (that a cellularity is a derived condition in many ‘multicellular’ lineages).

Biodiversity, speciation, and extinction trends of Proterozoic and Cambrian phytoplankton

The degradation-resistant organic-walled cell envelopes of acritarchs are the most abundant microfossils in Proterozoic and Cambrian rocks. These microfossils reveal diversity fluctuations that

The molecular ecology of microbial eukaryotes unveils a hidden world.

Actualistic taphonomy of cyanobacteria; implications for the Precambrian fossil record

Actualistic taphonomy can elucidate aspects of the fossil record that would otherwise be uninterpretable. Investigation of taphonomic alteration patterns in modern cyanobacteria permits evaluation of