Origins: According to Steve Richards, who wrote a couple of articles about these photographs for Western Mule Magazine, the pictures date from 2002 or 2003 and show Berry, a mule owned by Jody Anglin. Jody hunts mountain lions, and the incident depicted took place in southwestern New Mexico and came about as Berry the mule grew more aggressive over time in his pursuit of mountain lions with Jody:
When Jody first got the mule and after Jody shot the first lion out, Berry casually came over to the lion and just nuzzled the lion and casually nibbled it. With each lion Berry just got more aggressive. Jody said it didn't take more than two lions and Berry got really aggressive to the lion and couldn't wait to get the cat.
However, the text description accompanying these photographs is somewhat inaccurate, as Berry didn't actually kill the mountain lion — the mule picked it up and tossed it around only after it was already dead:
The lion was dead before the mule Berry took and shook the lion. A lion is a powerful and lethal predator and can easily kill a mule — however a mule can be quite an adversary.
Read more at
http://www.snopes.com/photos/animals/mulelion.asp#uFodhlglO4hR8zdw.99