Fósseis dos primeiros animais tipo esponja de 700 milhões de ano - Namíbia

terça-feira, fevereiro 07, 2012

The first animals: ca. 760-million-year-old sponge-like fossils from Namibia


C.K. ‘Bob’ Brain1 Anthony R. Prave2 Karl-Heinz Hoffmann3 Anthony E. Fallick4 Andre Botha5 Donald A. Herd2 Craig Sturrock6 Iain Young7 Daniel J. Condon8 Stuart G. Allison2 


1Ditsong Museum, Northern Flagship Institution, Pretoria, South Africa
2Department of Earth Sciences, University of St Andrews, St Andrews, UK
3Geological Survey, Ministry of Mines and Energy, Windhoek, Namibia
4Scottish Universities Environmental Research Centre, East Kilbride, UK
5Laboratory for Microscopy and Microanalysis, University of Pretoria, Pretoria, South Africa
6Environmental Sciences, University of Nottingham, Nottingham, UK
7School of Environmental and Rural Sciences, University of New England, Armidale, New South Wales, Australia
8NERC Isotope Geosciences Laboratory, Keyworth, UK

Correspondence to:

Anthony Prave

Postal address:
Department of Earth
Sciences, University of St
Andrews, St Andrews
KY16 9AL, UK

Received: 09 Mar. 2011
Accepted: 30 July 2011


One of the most profound events in biospheric evolution was the emergence of animals, which is thought to have occurred some 600–650 Ma. Here we report on the discovery of phosphatised body fossils that we interpret as ancient sponge-like fossils and term them Otavia antiqua gen. et sp. nov. The fossils are found in Namibia in rocks that range in age between about 760 Ma and 550 Ma. This age places the advent of animals some 100 to 150 million years earlier than proposed, and prior to the extreme climatic changes and postulated stepwise increases in oxygen levels of Ediacaran time. These findings support the predictions based on genetic sequencing and inferences drawn from biomarkers that the first animals were sponges. Further, the deposition and burial of Otavia as sedimentary particles may have driven the large positive C-isotopic excursions and increases in oxygen levels that have been inferred for Neoproterozoic time.