Feel at home when you crawl out of the sea

摘要

IT'S always good to have a bit of help to cross into the unknown. Some of the earliest creatures to crawl out of the ocean onto land half a billion years ago borrowed shells to carry a bit of the sea with them. This allowed them to survive in an otherwise hostile world, much like tanks of compressed air allow people to explore the deep ocean.rnPalaeontologist James Hagadorn of Amherst College in Massachusetts has been studying fossilised tracks left in sandstone in central Wisconsin, dating back 490 to 510 million years. At the time, vast sandy tidal flats fluctuated between wet and dry zones, thrusting organisms into new environments.