Evolution of multicellular animals began earlier than has been thought
The theory of Cambrian explosion states that most of the animal groups found today appeared for the first time some 545 million years ago within a short period of 5 to 10 million years. This is pretty well studied and amazing episode of Earth animal history , based on the fossil record indicates that diversity among animals forms evolved very rapidly during cambrian era . Recently researchers from scientists from UC Riverside, the Massachusetts Institute of Technology (and other institutions ) using the revolutionary new technology developed at The University of Nottingham have recorded the earliest evidence of animal life so far. Examination of sedimentary rocks in south Oman revealed anomalously huge amount of steroids dating back to 635 million years ago, which marks the end of ice age. These steroids are produced by Sponges belonging to Phyla Porifera .Sponges are simple multicellular animals and were considered to be most primitive animals till the latest studies of Phylogenomics stated otherwise.
Presence of sponges provides evidence of multicellular life forms 100 years before Cambrian explosion,which allow us to state that the evolution of multicellular animals began earlier than has been thought. Research led by Gordon Love will help scientists to reconstruct Earth’s early ecosystems and also explain how animal life may have first evolved on the planet.
They used a scientific technique known as Hydropyrolysis (using hydrogen gas at high pressure) ,which allowed them to release key biomarkers from ancient rocks with minimal structural alteration.
Normally scientists gets an idea about ancient life by fossilized remains of skeleton or by hardened remains of their footmarks. But things will become difficult in case of soft bodied animals and majority of ancient animals were of this kind . In order to gain more insights into soft bodied organisms of ancient times scientists have to come up with novel ways to uncover their presence in rocks and in earth crust. The new method employed by Love’s team involves detecting breakdown products from the lipid molecules,which over time Over time gets converted into a molecule known as cholestrane and in the case of sponges ,its mostly 24-isopropylcholestane.
The high-precision technique has shown that these fossil steroids, remnants Demosponges, are between 635 and 750 million years old. The details for the findings were published in latest issue of Nature, suggests that the shallow waters in some late Cryogenian ocean contained dissolved oxygen in concentrations sufficient to support simple multicellular animals at least 100 million years before the rapid diversification of bilaterians during cambrian era.
Reference :
Fossil steroids record the appearance of Demospongiae during the Cryogenian period.
Gordon D. Love, Emmanuelle Grosjean, Charlotte Stalvies, David A. Fike, John P. Grotzinger, Alexander S. Bradley, Amy E. Kelly, Maya Bhatia, William Meredith, Colin E. Snape, Samuel A. Bowring, Daniel J. Condon & Roger E. Summons
doi:10.1038/nature07673
Related press releases and links :
BBC : Sponges leaves their mark
NGC : Earliest Animals Were Sea Sponges, Fossils Hint
University of California, Riverside: Gordon Love
Kevin J. Peterson @ Dartmouth
Image Credit : Zoniedude / FlicKR
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