What is, has been

and will be again.

Evidence that Earth’s first mass extinction was caused by critters,

In the popular mind, mass extinctions are associated with catastrophic events, like giant meteorite impacts and volcanic super-eruptions. But the world’s first known mass extinction, which took place about 540 million years ago, now appears to have had a more subtle cause: evolution itself.

“People have been slow to recognize that biological organisms can also drive mass extinction,” said Simon Darroch, assistant professor of earth and environmental sciences at Vanderbilt University. “But our comparative study of several communities of Ediacarans, the world’s first multicellular organisms, strongly supports the hypothesis that it was the appearance of complex animals capable of altering their environments, which we define as ‘ecosystem engineers,’ that resulted in the Ediacaran’s disappearance.”

One creature's poison is another's energy source

The earliest life on Earth consisted of microbes – various types of single-celled microorganisms. They ruled the Earth for more than 3 billion years. Then some of these microorganisms discovered how to capture the energy in sunlight. The photosynthetic process that they developed had a toxic byproduct: oxygen. Oxygen was poisonous to most microbes that had evolved in an oxygen-free environment, making it the world’s first pollutant.

Now I am still a "luke-warmist" when it comes to the whole climate debate but even if I am wrong, I'm thinking we'll leave behind some cooler fossils than those plain Jane Ediacarans.