Oldest footprints discovered in 540-mn-yr-old insect tracks 
The oldest known footprints on Earth, left by ancestors of modern-day insects at least 541 million years ago, have been discovered in China. Scientists couldn't ascertain what the creature looked like, but said nothing this old with legs had been discovered to date. The fossils, few millimetres in width, were spotted by tilting rock slabs at different angles against sunlight.