I'm going to take a quick break from our trip to Yosemite to share a photo with you. I saw this on Wikipedia's featured pictures page and it comes courtesy of the Burton Historical Collection at the Detroit Public Library.
What you're seeing is photo from about 1870 of a pile of bison skulls waiting to be ground into fertilizer.
Bison are amazing creatures. If visit California, you can see a wild non-native heard on Catalina Island, about 22 miles off of Los Angeles. They were brought to the island for a 1924 silent-era film.