Os primeiros ecossistemas da Terra eram mais complexos do que antes considerados

sábado, novembro 28, 2015

Suspension feeding in the enigmatic Ediacaran organism Tribrachidium demonstrates complexity of Neoproterozoic ecosystems

Imran A. Rahman 1, Simon A. F. Darroch 2, 3,*, Rachel A. Racicot 2, 4 and Marc Laflamme 5

- Author Affiliations

1School of Earth Sciences, University of Bristol, Life Sciences Building, 24 Tyndall Avenue, Bristol BS8 1TQ, UK.

2Smithsonian Institution, P. O. Box 37012, MRC 121, Washington, DC 20013–7012, USA.

3Department of Earth and Environmental Sciences, Vanderbilt University, 2301 Vanderbilt Place, Nashville, TN 37235–1805, USA.

4The Dinosaur Institute, Natural History Museum of Los Angeles County, Los Angeles, CA 90007, USA.

5Department of Chemical and Physical Sciences, University of Toronto Mississauga, 3359 Mississauga Road, Mississauga, Ontario L5L 1C6, Canada.

↵*Corresponding author.
E-mail: simon.a.darroch@vanderbilt.edu

Science Advances 27 Nov 2015:

Vol. 1, no. 10, e1500800

DOI: 10.1126/sciadv.1500800

Source/Fonte: Science Advances


The first diverse and morphologically complex macroscopic communities appear in the late Ediacaran period, 575 to 541 million years ago (Ma). The enigmatic organisms that make up these communities are thought to have formed simple ecosystems characterized by a narrow range of feeding modes, with most restricted to the passive absorption of organic particles (osmotrophy). We test between competing feeding models for the iconic Ediacaran organism Tribrachidium heraldicum using computational fluid dynamics. We show that the external morphology of Tribrachidium passively directs water flow toward the apex of the organism and generates low-velocity eddies above apical “pits.” These patterns of fluid flow are inconsistent with osmotrophy and instead support the interpretation of Tribrachidium as a passive suspension feeder. This finding provides the oldest empirical evidence for suspension feeding at 555 to 550 Ma, ~10 million years before the Cambrian explosion, and demonstrates that Ediacaran organisms formed more complex ecosystems in the latest Precambrian, involving a larger number of ecological guilds, than currently appreciated.

Keywords Ediacara Ecology suspension feeding ecosystem engineers computational fluid dynamics

Copyright © 2015, The Authors

This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial license, which permits use, distribution, and reproduction in any medium, so long as the resultant use is not for commercial advantage and provided the original work is properly cited.

FREE PDF GRATIS: Science Advances