Coahuilaceratops (“Coahuila horned face”) was the first ceratopsid discovered in Mexico, living about 72-71 million years ago. Known from partial skull material and other fragmentary remains, it’s estimated to have measured around 5-6m in length (16′4″-19′8″)
It seems to have been an early member of a branch of the chasmosaur evolutionary tree that included animals more closely related to Chasmosaurus than to Triceratops. (This grouping doesn’t currently have an official name, but similarly to @a-dinosaur-a-day I’ll be referring to them as the “Chasmosaurini”.)
Its brow horns were proportionally huge for its size, each reaching up to 1.2m long (4′) – some of the largest of all known ceratopsids.