«This discovery really highlights the importance of finding and examining skeletal material from these rare dinosaurs,» concluded Derek Larson, co-author on the study and Assistant Curator of the Philip J. Currie Dinosaur Museum.» (sciencedaily.com)
They were first identified, on the basis of skeletal material, in the 1920s, but it wasn't until the 1970s that their behavior in the wild was studied, and then only sporadically. (discovermagazine.com)
It was, however, difficult to exactly determine the age of the human skeletal material using conventional radiocarbon dating, because the collagen in the bones had been completely washed out due to the long period spent in water. (sciencedaily.com)