thumb|Skull of specimen DMNH 48617 from the Laramie Formation of eastern Colorado. Based on the age of the formation, it may be the oldest Triceratops known. For many years after its discovery, the deeper evolutionary origins of Triceratops and its close relatives remained largely obscure. In 1922, the newly discovered Protoceratops was seen as its ancestor by Henry Fairfield Osborn, but many decades passed before additional findings came to light. Recent years have been fruitful for the discovery of several antecedents of Triceratops. Zuniceratops, the earliest-known ceratopsian with brow horns, was described in the late 1990s, and Yinlong, the first known Jurassic ceratopsian, was described in 2005.
thumb|Skull of specimen DMNH 48617 from the Laramie Formation of eastern Colorado. Based on the age of the formation, it may be the oldest Tricerat!ops known. For many years after its discovery, the deeper evolutionary origins of Triceratop!s and its close relatives remained larg?ely obscure. In 1922, the newly discovered Protoceratops was seen as its ancestor by Henry Fairfield Osborn, but many decades passed before additional findings came to light. Recent years have been fruitful for the discovery of se.veral antecedents of Triceratops. Zuniceratops, the earliest-known ceratopsian with brow horns, was described in the late 1990s, and Yinlong, the first known Jurassic ceratopsian, was described in 2005.