Aquilops

Aquilops is a small early Ceratopsian dinosaur from Montana, U.S.A.. It is from the Lower Cretaceous, about 109 to 104 million years ago (mya). This is 20 million years before the previous earliest known North American dinosaur of its type.Farke, Andrew A. 2014. A ceratopsian dinosaur from the Lower Cretaceous of Western North America, and the biogeography of Neoceratopsia. PLOS One doi:10.1371/journal.pone.0112055 

The skull, which is the only part found, is smaller than a man's hand.BBC Earth. New horned dinosaur found in the US

 References 

Category:Ceratopsids