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Ancient Rocks Give a Glimpse Into Life Before Oxygen

Somewhere between Earth's creation and where we are today, scientists have demonstrated that some early life forms existed just fine without any oxygen.
While researchers proclaim the first half of our 4.5 billion-year-old planet's life as an important time for the development and evolution of early bacteria, evidence for these life forms remains sparse including how they survived at a time when oxygen levels in the atmosphere were less than one-thousandth of one percent of what they are today.

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New Bacteria Groups, and Stunning Diversity, Discovered Underground

One of the most detailed genomic studies of any ecosystem to date has revealed an underground world of stunning microbial diversity, and added dozens of new branches to the tree of life.
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3 billion-year-old fossils show early microbes lived in cavities

It seems the microbes that formed Earth's first ecosystems looked for shade when the sun was strong, just like we do.
Fossils found in South Africa suggest that cavities in tidal sediments might have provided refuge from deadly solar rays during the Archaean aeon when we think that life emerged on Earth
At this time, between 4 billion and 2.5 billion years ago, Earth was scorched by intense UV radiation, and had no ozone layer to protect it - a bit like Mars is today.
At the Barberton greenstone belt in South Africa, an area where ancient volcanic rock has been pushed to the surface, there are thin layers of rock thought to be 3.22 billion-year-old microbial mats - sheets of microbes that covered tidal areas of the seashore.

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Complex life
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Revealed - the single event that made complex life possible in our oceans

The catalyst that allowed the evolution of complex life in Earth's oceans has been identified by a University of Bristol researcher. Up to 800 million years ago, the Earths oceans were deprived of oxygen. It was only when microorganisms called phytoplankton, capable of performing photosynthesis, colonised the oceans - covering two thirds of our planet - that production of oxygen at a massive scale was made possible.
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Hallucigenia
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Weird fossil worm with legs and spikes finally reveals its head

Hallucigenia was a worm-like marine animal with legs, spikes and a head that is difficult to distinguish from its tail. It is only a few centimetres long, and its body is as thin as a pin.
This enigmatic 508-million-year-old worm-like creature has been tricking scientists since the 1970s. Reconstructions of what it would have looked like had it upside down, on its side and even back to front.
Now Martin Smith of the University of Cambridge and his colleagues think they finally have the correct description of this creature, which lived during the Cambrian explosion when most major animal groups first emerge in the fossil record.

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Title: Paleoarchean trace fossils in altered volcanic glass
Author: Hubert Staudigel, Harald Furnes, and Maarten DeWit

The dawn of sustainable life on earth is preserved in the form of fossil or chemical evidence in ancient rock sequences, such as the Barberton Greenstone Belt in South Africa. Studies of sedimentary rocks offered a glimpse at life at the earth's surface, and trace fossils in pillow lavas offered evidence for a potential deep biosphere back in time to the Paleoarchean. Recent data cast doubt on the biogenicity of these putative trace fossils, rejecting their potential in exploring a deep biosphere. We discuss biogenicity of Cenozoic and Archean examples of such putative biocorrosion textures and conclude that microbial origin remains the best explanation for the textures described previously in these Paleoarchean rocks (e.g., >3.4 Ga).

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Oldest fossils controversy resolved

New analysis of world-famous 3.46 billion-year-old rocks by researchers from the University of Bristol, the University of Oxford and UWA (the University of Western Australia) is set to finally resolve a long running evolutionary controversy.
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Early life hunt inspired by oldest fossils debate

A team from Oxford University, the University of Bristol, and the University of Western Australia has analysed 3.46 billion-year-old rocks containing structures once thought to be Earths oldest microfossils. The team present high-spatial resolution data that show these 'Apex chert microfossils' do not match younger fossils of microscopic life and instead comprise peculiarly-shaped minerals.
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Chinese scientists have discovered a 600 million-year-old sponge-like fossil, predating existing findings of primitive animals by 60 million years.
The Nanjing Institute of Geology and Paleontology at the Chinese Academy of Sciences on Monday said that the tiny fossil, which only measures two to three cubic millimeters, was discovered in the Weng'an biota in the southwest province of Guizhou.

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Coated droplets hint at formation of early cells

Researchers at the University of Bristol have designed a chemical system that brings together alternative ideas on how primitive cells were formed on the early Earth to produce a new model of protocell organization. The work is described in an article published this week in Nature Chemistry.
The most fundamental requirement for the emergence of cells on the early Earth is the existence of a closed compartment, but how this came about remains a mystery.

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