The Avalon Explosion: Evolution of Ediacara Morphospace

  title={The Avalon Explosion: Evolution of Ediacara Morphospace},
  author={Bing Shen and Lin Dong and Shuhai Xiao and Michał Kowalewski},
  pages={81 - 84}
Ediacara fossils [575 to 542 million years ago (Ma)] represent Earth's oldest known complex macroscopic life forms, but their morphological history is poorly understood. A comprehensive quantitative analysis of these fossils indicates that the oldest Ediacara assemblage—the Avalon assemblage (575 to 565 Ma)—already encompassed the full range of Ediacara morphospace. A comparable morphospace range was occupied by the subsequent White Sea (560 to 550 Ma) and Nama (550 to 542 Ma) assemblages… 

The rise of bilaterians

While genera with both kinds of symmetry properties and unitary and colonial animals were present during the early Ediacaran, there was a large proportional increase in new bilaterian genera and a decrease in colonial genera beginning between 560–550 MA.

An early Ediacaran assemblage of macroscopic and morphologically differentiated eukaryotes

A diverse assemblage of morphologically differentiated benthic macrofossils that were preserved largely in situ as carbonaceous compressions in black shales of the Ediacaran Lantian Formation suggests that morphological diversification of macroscopic eukaryotes may have occurred in the early Ediacaren Period, and that the redox history of Ediacaru oceans was more complex than previously thought.

A morphospace of planktonic marine diatoms. I. Two views of disparity through time

Although the increase in occupied volume through time ostensibly supports a conclusion of increasing morphological variety, sampling biases and other data suggest an underlying stationary pattern more consistent with molecular clock data.

Restricted morphospace occupancy of early Cambrian reef-building archaeocyaths

Abstract. The evolution of novel morphologies can signify expansion of a clade into new niches. This can be studied in the fossil record by investigating the morphospace occupancy of organisms,

Ediacaran distributions in space and time: testing assemblage concepts of earliest macroscopic body fossils

Abstract. The mid-late Ediacaran Period (∼579–541 Ma) is characterized by globally distributed marine soft-bodied organisms of unclear phylogenetic affinities colloquially called the “Ediacara

Fractal branching organizations of Ediacaran rangeomorph fronds reveal a lost Proterozoic body plan

Using parametric Lindenmayer systems, a formal model of rangeomorph morphologies reveals a fractal body plan characterized by self-similar, axial, apical, alternate branching, which demonstrates an adaptive radiation based on 3D space-filling strategies.

Fractal branching organizations of Ediacaran rangeomorph fronds reveal a lost Proterozoic body plan

Using parametric Lindenmayer systems, a formal model of rangeomorph morphologies reveals a fractal body plan characterized by self-similar, axial, apical, alternate branching, and an adaptive radiation based on 3D space-filling strategies.

Remarkable insights into the paleoecology of the Avalonian Ediacaran macrobiota

Major Evolutionary Trends

  • M. Hughes
  • Environmental Science, Geography
  • 2013
This work addresses the evolution of disparity in metazoans across the Phanerozoic and the disparity of bivalves across the Palaeozoic, finding disparity rises across time but not decreased by mass extinctions.



Paleozoic record of morphologica diversity in blastozoan echinoderms.

  • M. Foote
  • Environmental Science, Geography
    Proceedings of the National Academy of Sciences of the United States of America
  • 1992
Analysis of discrete morphological characters shows that initial morphological diversification in the echinoderm subphylum Blastozoa was so pronounced that Morphological diversity relative to taxonomic diversity was greatest in the Cambrian, whereas morphological diversity itself was greatestIn the Middle and Upper Ordovician.

Biostratigraphic and Geochronologic Constraints on Early Animal Evolution

Two distinct evolutionary pulses, represented by the Vendian Ediacaran fauna and Cambrian small shelly faunas, are generally thought to characterize the emergence of macroscopic animals at the end of

THE EDIACARA BIOTA: Neoproterozoic Origin of Animals and Their Ecosystems

Present evidence suggests that the Ediacara biota included a mixture of stem- and crown-group radial animals, stem-group bilaterian animals, “failed experiments” in animal evolution, and perhaps representatives of other eukaryotic kingdoms.

Morphological disparity in Ordovician-Devonian crinoids and the early saturation of morphological space

  • M. Foote
  • Environmental Science
  • 1994
Comparison with generic richness reveals that the full range of form was essentially attained by the early part of the Caradocian, long before the time of maximal taxonomic diversity.

Life after snowball: The oldest complex Ediacaran fossils

Newly discovered fronds of the Ediacaran index fossil Charnia from the Drook Formation of southeastern Newfoundland are the oldest large, architecturally complex fossils known anywhere. Two species

Patterns of distribution in the Ediacaran biotas: facies versus biogeography and evolution

Abstract The siliciclastic succession of the late Neoproterozoic Vendian Group in the White Sea area demonstrates a wide range of lithofacies, some recurring in a vertical succession. Significantly,

The Ediacaran Biotas in Space and Time1

  • B. Waggoner
  • Environmental Science, Geography
    Integrative and comparative biology
  • 2003
It is concluded that the Ediacaran organisms show a diverse range of responses to various environmental parameters, and there is no basis for classifying them all as having a single body plan and mode of life.

Underground Vendobionta From Namibia

The late Precambrian fossils from Namibia have generally been regarded as soft‐bodied organisms whose three‐dimensional preservation resulted from smothering in fluidized sand. The sedimentological


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