What type of mammal does this fossil tooth belong to? The fossil tooth was found western South Dakota in the early 1980s.
I can't be sure on the location.  It might have been collected from Belle Reservoir, near Belle Fourche, Butte County, South Dakota, USA.
What type of mammal does this fossil tooth belong to?
It's an entelodont, South Dakota is famous for it's Oligocene mammalian faunas which include entelodonts such as Archaeotherium and Daeodon. 


here is an http://i.ebayimg.com/images/i/181202162847-0-1/s-l1000.jpg for comparison:


Thanks to the guys at fossilforum, they knew in less than a day. this question could have stayed on here for a year so i was impatient.