12,000 fossils in 1.7B-year-old Australian rocks reveal clues to complex life

More than 12,000 microscopic fossils recovered from 1.7-billion-year-old rocks in northern Australia are offering scientists a rare glimpse into the early history of complex life. The fossils belonged to ancient eukaryotes, the broad group that includes animals, plants, fungi and algae. They lived long before animals appeared, yet their cells already had a complexity far beyond that of bacteria and archaea. According to ScienceDaily, researchers studied mudstone cores stored by the Northern Territory Geological Survey and found that the fossil organisms lived in environments containing oxygen, from coastal mudflats to the open sea. Oxygen-free samples contained only simpler microbial forms.