I find this totally facsinating. It's the featured picture on the Wikipedia homepage:
Here's the caption that went with it:
Photograph from the mid-1870s of a pile of American Bison skulls waiting to be ground for fertilizer. Bison were hunted almost to extinction in the 19th century and were reduced to a few hundred head by the mid-1880s, from which all the present day's managed herds are descended. The commercial take arguably was anywhere from 2,000 to 100,000 animals per day, though there are no statistics available.
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I've always heard that the American Bison was hunted practically to extinction and I've always accepted it as fact, but I've never really gotten how a whole species could, within the course of only a handful of decades, be almost completely wiped out. This picture made it a little clearer for me.