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Ancient rocks show high oxygen levels on Earth 2 billion years ago by Staff Writers Edmonton, Canada (SPX) May 13, 2020
Earth may have been far more oxygen-rich early in its history than previously thought, setting the stage for the evolution of complex life, according to new research by scientists at the University of Alberta and the University of Tartu in Estonia. The study provides evidence for elevated oxygen levels 2 billion years ago and flies in the face of previously accepted models. The international team of researchers, led by UAlberta scientists, studied a Russian drill core containing shungite - a unique carbon-rich sedimentary rock deposited 2 billion years ago. The material provides several clues about oxygen concentrations on Earth's surface at that time, including strikingly high levels of molybdenum, uranium, and rhenium, as well as elevated uranium isotope ratios. "These trace metals are only thought to be common in Earth's oceans and sediments when oxygen is abundant," explained Kaarel Mand, a PhD candidate in the University of Alberta's Department of Earth and Atmospheric Sciences and lead author of the study. "These trace metal concentrations are unrivaled in early Earth's history, suggesting elevated levels of oxygen at the time when the shungite was deposited." What's puzzling, Mand explained, is that many widely accepted models of Earth's carbon and oxygen cycles predict that shungite should have been deposited at a time of rapid decrease in oxygen levels. "What we found contradicts the prevailing view," says Mand, who is completing his PhD under the supervision of Professor Kurt Konhauser. "This will force the Earth science community to rethink what drove the carbon and oxygen cycles on the early Earth." The new findings also provide insight into the evolution of complex life. Earth's "middle age" represents the backdrop for the appearance of eukaryotes. Eukaryotes are the precursors to all complex life, and require high oxygen levels in their environment to thrive. This study strengthens the idea that suitable conditions for the evolution of complex life on early Earth began much earlier than previously thought. Future research will examine the delay between the initial rise of oxygen and the appearance and spread of eukaryotes, remaining an area of active research, one that University of Alberta and University of Tartu researchers are well positioned to help answer.
Research Report: "Paleoproterozoic oxygenated oceans following the Lomagundi-Jatuli Event"
Early marine reptiles used pebble-like teeth to crush shellfish Washington (UPI) May 8, 2019 Some early ichthyosaurs used rounded, pebble-like teeth to crush the shells of snails and clam-like bivalves, according to new research. Roughly 252 million years ago, the end-Permian Mass extinction wiped out 90 percent of the planet's marine species and 70 percent of terrestrial species. Ichthyosaurs were one of the few benefactors. The marine tetrapods rapidly diversified, taking advantage of a variety of vacated environs. The fossil record suggests ichthyosaurs quickly established th ... read more
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