Trilobites: Long Before Making Enigmatic Earthworks, People Reshaped Brazil’s Rain Forest

Deep in the Amazon, the rain forest once covered ancient secrets. Spread across hundreds of thousands of acres are massive, geometric earthworks. The carvings stretch out in circles and squares that can be as big as a city block, with trenches up to 12 yards wide and 13 feet deep.

Saiga Antelopes Are Struck Again by a Plague in Central Asia

They found the first carcasses in late December, on the frozen steppes of Mongolia’s western Khovd province. By the end of January, officials in the region had recorded the deaths of 2,500 endangered saiga antelopes — about a quarter of the country’s saiga population — and scientists had identified a culprit: a virus called peste des petits ruminants, or P.P.R.