A ceratopsian horncore from the Olmos Formation (early Maastrichtian) near Múzquiz, Mexico

Abstract

An isolated supraorbital horncore collected from the Olmos Formation near Múzquiz is among the longest ever found, and records the presence in this area of a very large ceratopsid. The specimen probably pertains to a chasmosaurine, but differs significantly from the horncores in Coahuilaceratops known from the nearby Cerro del Pueblo Formation, and cannot be attributed with confidence to any other known ceratopsid.