#chasmosaurines

Coahuilaceratops, a genus of chasmosaurine ceratopsian dinosaur, is thought to have possessed among the largest horns of any known dinosaur, even though it is based on incomplete remains. Its horns may have rivaled the size of those of larger chasmosaurines such as Triceratops and Torosaurus, at 1.2 m (4 ft) long.

There has been debate over the function of the frills and horns on Triceratops and other similar species. Most recent interpretations find that they would have been used in species identification and courtship, similar to modern ungulates, as opposed to fending off predators.

The Tyrannosaurus and the Triceratops, from the 1992 documentary "The Dinosaurs! Flesh on the Bones".

For my own part, I first saw this animation on a 1993 Windows interactive dinosaurs CD-ROM, along with the famous Phil Tippett short "Prehistoric Beast".