During the Permian Period many tetrapods, or four-limbed vertebrates, took to life in the trees.
Around 300 million years ago sails were all the rage, but we're still not sure what they were for.
For millions of years after the Great Dying microbes ruled the Earth.
Gigantic black holes existed in a cosmic eyeblink after the Big Bang. That should be impossible.
Bob Ross paints a golden field of sparse pines and other greenery.