Five mass extinctions—and what we can learn from them about the planet today
June 29, 2017 by Alex Dunhill, The Conversation
Of all the species that have ever lived, more than 99% are now extinct. Most of them quietly disappeared during periods of "background extinction", whereby a handful of species become extinct every 100,000 years or so.
But there were also occasions when extinction rates increased rapidly in short periods of time and wiped out a significant proportion of all life on Earth. These are known as mass extinctions. They have profoundly influenced the history of life – and many scientists now argue that we are in the midst of another one. To see if they're right, we can look at previous occasions when large numbers of species went extinct.
https://phys.org/news/2017-06-mass-extinctionsand-planet-today.html
