 The first ceratopsian remains known to science were discovered during the U.S. Geological and Geographical Survey of the Territories led by the American geologist <unk> <unk> . <unk> discovered during an 1855 expedition to Montana were first assigned to hadrosaurids and included within the genus Trachodon . It was not until the early 20th century that some of these were recognized as ceratopsian teeth . During another of <unk> 's expeditions in 1872 , Fielding Bradford <unk> found several giant bones protruding from a hillside in southwestern Wyoming . He alerted paleontologist Edward <unk> Cope , who led a dig to recover the partial skeleton . Cope recognized the remains as a dinosaur , but noted that even though the fossil lacked a skull , it was different from any type of dinosaur then known . He named the new species Agathaumas <unk> , meaning " marvellous forest @-@ dweller " . Soon after , Cope named two more dinosaurs that would eventually come to be recognized as ceratopsids : <unk> and Monoclonius . Monoclonius was notable for the number of <unk> remains found , including the first evidence of ceratopsid horns and frills . Several Monoclonius fossils were found by Cope , assisted by Charles <unk> Sternberg , in the summer of 1876 near the Judith River in <unk> County , Montana . Since the ceratopsians had not been recognised yet as a distinctive group , Cope was uncertain about much of the fossil material , not recognizing the nasal horn core , nor the brow horns , as part of a fossil horn . The frill bone was interpreted as a part of the <unk> . 
