In early August 1910, Barnum Brown during an American Museum of Natural History expedition discovered a large dinosaur skeleton in the Dry Island site, on the west bank of the Red Deer River in southern Alberta, Canada.
The holotype specimen, RTMP 2002.57.5, has been found in a layer of the uppermost Horseshoe Canyon Formation, dated to the early Maastrichtian, about 67.6 million years ago.