Chasmosaurus belli Lambe, 1902

Monoclonius belli Lambe 1902: 59

Monoclonius canadensis Lambe 1902: 63 Ceratops belli Hatcher et al. 1907: 97

Ceratops canadensis Hatcher et al. 1907: 97 Protorosaurus belli Lambe 1914: 131

Chasmosaurus belli Lambe 1914: 149

Eoceratops canadensis Lambe 1915: 2

Chasmosaurus kaiseni Brown 1933: 2

Chasmosaurus brevirostris Lull 1933: 94 Chasmosaurus canadensis Lehman 1989: 139

Amended diagnosis. Taxon displaying the combination of characters unique to the genus Chasmosaurus along with the following features: (1) parietal posterior bar bearing no median emargination and is nearly straight so that it forms a ‘T’ shape with the parietal median bar; (2) lateral pair of epiparietals large and triangular; others, when preserved, are smaller (after Godfrey & Holmes 1995). Both characters are autapomorphic for C. belli within Chasmosaurus.

Holotype. CMN 491, a partial parietal. Although fragmentary, the holotype is diagnostic based on the combination of generic character 4, and specific character 1, a combination not observed in any other chasmosaurine. Distribution. Middle and upper beds of the Dinosaur Park Formation, Alberta, Canada (Ryan & Evans 2005).

Referred specimens. CMN 2245; AMNH 5402; ROM 843; YPM 2016; NHMUK R4948 (after Ryan & Evans 2005). The NHMUK specimen is referred to Chasmosaurus because it possesses characters 1, 3, 4 and 5 from the diagnosis of Chasmosaurus (above); it is referred to C. belli because it possesses character 1 from the diagnosis of C. belli (above).

Specimens removed from C. belli. ROM 839 was referred to C. belli by Ryan and Evans (2005) and Longrich (2010), but is not diagnosable to species level based on the amended diagnosis presented here and represents Chasmosaurus sp.