Original sentence: Their work in Port Simpson covered every imaginable facet of Tsimshian culture, including especially social structure -- this at the instigation of Boas, whose own Tsimshian monograph had been upstaged by Beynon and Marius Barbeau's published Tsimshian research
Edited sentence: Their work in Port Simpson covered every imaginable facet of Tsimshian culture, including especially social structure—this at the instigation of Boas, whose own Tsimshian monograph had been upstaged by Beynon and Marius Barbeau's published Tsimshian research