YOU'RE RIGHT! All of the above. Prehistoric bison were 5,000 pounds. Bull bison can be 1,400-3,000 pounds, and cows can be 900-1,200 pounds. Nickel weighed about 1400 pounds! Mature bulls are 6’ tall at the shoulders and 9’- 12’ long. Cows are 5’ tall at the shoulders and 7’-10’ long.