Monoclonius was named by Edward Drinker Cope in 1876 , soon after the first fossil specimen ( a near complete skeleton including skull material and the pbase of the nasal horn , with only the feet missing ) had been founded in Montana . The type specimen was found in the summer of 1876 in Montana , only about 100 miles from the site of the Battle of the Little Bighorn that June . Although it was not an articulated skeleton , Cope recovered most of the animal ( only the feet were entirely missing ) , including skull material and the base part of a long nasal horn .