Well, it's official. After weeks of searching, scientists have declared the Yangtze River dolphin (or baiji) extinct. Weighing up to 500 pounds, thousands of baiji could once be found in the Yangtze River but hunting, destructive fishing practices, and industrialization was more than this ancient marine mammal could handle.

Whenever something goes extinct, I'm always reminded of Aldo Leopold's famous essay about the death of the last passenger pigeon: "Men still live who, in their youth remember pigeons; trees still live that, in their youth, were shaken by a living wind. But a few decades hence only the oldest oaks will remember, and at long last only the hills will know."