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

Significance Rangeomorph fronds characterize the late Ediacaran Period (575–541 Ma), representing some of the earliest large organisms. As such, they offer key insights into the early evolution of multicellular eukaryotes. However, their extraordinary branching morphology differs from all other orga...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 2014-09, Vol.111 (36), p.13122-13126
Main Authors: Cuthill, Jennifer F. Hoyal, Morris, Simon Conway
Format: Article
Language:English
Subjects:
Animal morphology
Animal Structures - anatomy & histology
Animals
Biological Sciences
Biota
Extinction
Fossils
Fractals
Imaging, Three-Dimensional
Marine ecology
Morphology
Nutrient uptake
Oceans
Parametric models
Surface areas
Taxa
Time Factors
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Summary:Significance Rangeomorph fronds characterize the late Ediacaran Period (575–541 Ma), representing some of the earliest large organisms. As such, they offer key insights into the early evolution of multicellular eukaryotes. However, their extraordinary branching morphology differs from all other organisms and has proved highly enigmatic. Here we provide a unified mathematical model of rangeomorph branching, allowing us to reconstruct 3D morphologies of 11 taxa and measure their functional properties. This reveals an adaptive radiation of fractal morphologies which maximized body surface area, consistent with diffusive nutrient uptake (osmotrophy). Rangeomorphs were adaptively optimal for the low-competition, high-nutrient conditions of Ediacaran oceans. With the Cambrian explosion in animal diversity (from 541 Ma), fundamental changes in ecological and geochemical conditions led to their extinction.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.1408542111