 Gorgosaurus libratus was first described by Lawrence Lambe in 1914 . Its name is derived from the Greek <unk> / <unk> ( " fierce " or " terrible " ) and σαυρος / saurus ( " lizard " ) . The type species is G. libratus ; the specific epithet " balanced " is the past participle of the Latin verb <unk> , meaning " to balance " . 
