OXYGEN OASIS Oxygen was abundant enough for complex life-forms such as this 1.4-billion-year-old fossilized eukaryote to thrive around 2.3 billion years ago, new research suggests. The expansion and diversification of eukaryotes nevertheless only came hundreds of millions of years later.
Andrew Knoll/Harvard University
SUPERCONTINENT SUPERPUZZLE Supercontinents come and go over the ages. Amasia, illustrated here from the North Pole, might form in the distant future.
Nicolle Rager Fuller
A 100-meter-wide, kilometers-long rift in Antarctica’s Larsen C ice shelf, shown in this image from Nov. 10, 2016, could soon break off a 5,000-square-kilometer chunk of ice into the ocean, scientists warn.