. The Canadian field-naturalist. Natural history; Sciences naturelles. 404 The Canadian Field-Naturalist Vol. 120. Figure 2. CMN 2280 (left) and CMN 2245 (right) on display at the National Museum of Canada (circa 1926). (Courtesy of the Canadian Museum of Nature). As restored, the skeletons measured "approximately the same length but the bones of are much Ughter in construction than those of the other" (Sternberg 1927: 67). According to Sternberg, the total length of the 'gracile' skeleton measured m, while that of the "robust" skeleton measured m. Unfortun
. The Canadian field-naturalist. Natural history; Sciences naturelles. 404 The Canadian Field-Naturalist Vol. 120. Figure 2. CMN 2280 (left) and CMN 2245 (right) on display at the National Museum of Canada (circa 1926). (Courtesy of the Canadian Museum of Nature). As restored, the skeletons measured "approximately the same length but the bones of are much Ughter in construction than those of the other" (Sternberg 1927: 67). According to Sternberg, the total length of the 'gracile' skeleton measured m, while that of the "robust" skeleton measured m. Unfortunately, their supports have since been disassembled and these original measurements cannot be verified. Sternberg attributed the difference in robustness between the two specimens to sexual dimorphism, stating, "it is thought that they represent male and female as it is common, among reptiles, for the female to be larger than the male" (Sternberg 1927: 67). This assumption has gone largely unchallenged in the literature ( Lull 1933; Carpenter and Carrie 1990; Dodson 1996), except for an implication by Godfrey and Holmes (1995) that the reported differences between the specimens do not reflect sexual dimorphism because they pertain to two separate species of Chasmosaurus. The recognition of sexual dimorphism in a fossil species must begin with the establishment that the vari- ation observed within that species does represent dimor- phism. With only two reasonably complete skeletons of Chasmosaurus belli at his disposal, Sternberg could not have established this with certainty, and indeed, he neither quantified nor qualified the differences he observed between the specimens. It is also important to note that many of the bones were highly reconstruct- ed with plaster and subsequently painted over so that the reconstructed portions cannot be easily identified. As chronicled by C. H. Sternberg (C. M. Sternberg's father) regarding the restoration of one of the skulls: &
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