Ocean tides as evolutionary triggers

New calculations suggest that, around 400 million years ago, many coastlines experienced two-week tidal cycles that varied in height by four metres or more. Such a huge range could have stranded fish in tidal pools for a couple of weeks. Only the ones with fins strong enough to muscle themselves out would have been able to journey back into the ocean and survive. Fossil evidence for the earliest known land vertebrates comes from places that had such wide tidal ranges...

Hundreds of millions of years ago, the Moon was much closer to Earth than it is now. Steven Balbus, an astrophysicist at the University of Oxford, UK, has explored how the Moon’s proximity to Earth might have affected its gravitational pull and influenced life on the planet. In 2014, he suggested that Earth’s tidal ranges would have been greater around the time the first four-limbed vertebrates, or tetrapods, appeared on land...

More information at Nature.