 Gorgosaurus ( / ˌɡɔːrɡəˈsɔːrəs / GOR @-@ gə @-@ SOR @-@ əs ; meaning " dreadful lizard " ) is a genus of tyrannosaurid theropod dinosaur that lived in western North America during the Late Cretaceous Period , between about 76 @.@ 6 and 75 @.@ 1 million years ago . Fossil remains have been found in the Canadian province of Alberta and possibly the U.S. state of Montana . Paleontologists recognize only the type species , G. libratus , although other species have been erroneously referred to the genus . 
