Inside a Crimean cave was a gigantic ancient mystery just waiting to be uncovered: a bird so large that it weighed nearly as much as an adult polar bear. Giant birds once roamed Madagascar, New Zealand and Australia. The latest fossil find, an intriguing fossilized femur, was recently found in Taurida Cave on the northern coast of the Black Sea. It was discovered along with other fossils, including bison bones, that helped researchers date the now-extinct giant bird to between 1.5 million and 2 million years ago. When the first early human ancestors arrived in Europe, they might have encountered...