Ceratosaurus means "horned lizard," and is pronounced: sir-AT-oh-SORE-us. It lived in North America during the late Jurassic, and was a small-to-medium sized theropod, at 15 feet long and weighing about one ton.

The distinguishing feature of Ceratosaurus are the horns above its eyes and, more notably, on its snout, which can be seen better here: http://upload.wikimedia.org/wikiped.....ratosaurus.jpg
It was unlikely that the horn was used offensively, but instead more of a sexually selected characteristic; that is, Ceratosaurus males with more prominent horns had precedence when mating with females.

At the Museum of Ancient Life, Thanksgiving Point, Utah.