APPENDIX

Dimensions of the models used in this study were compared with dimensions of the original specimen, to evaluate the models' accuracy. The measurements for the original specimen, YPM 1822, are taken from Hatcher et al. (1907), and the measurements of the model were made using sliding calipers. The model's dimensions range from 12.1% to 22.4% of the dimensions given by Hatcher, with an average value of 14.8%. The measurements for the model and the original specimen have a correlation coefficient of .977, with an R² value of .955, p<.005. All measurements are in millimeters. A slight difference in nasal horn orientation exists between the model and the original specimen. Given the variation in cranial form within Triceratops (see Discussion), this difference was not considered to be of great importance.

Measurement	Original Specimen	Model	Percent
Length of skull from distal tip of nasal horn core to caudal border of parietal	1383	202	14.6%
Greatest width of frill	944	165	17.5%
Width across squamosal rostro-ventral borders	556	67	12.1%
Width across distal ends of epijugals	532	89	16.7%
Distance from rostral border of orbit to apex of rostral	712	102	14.3%
Distance from orbit to tip of nasal horn core	660	89	13.5%
Distance between orbits	245	55	22.4%
Distance from ventral border of orbit to distal tip of jugal	340	50	14.7%
Rostro-caudal orbit diameter	128	16	12.5%
Dorso-ventral orbit diameter	122	16	13.1%
Distance from dorsal border of orbit to tip of postorbital horncore	550	84	15.3%
Distance from tip of postorbital horncore to tip of nasal horncore	650	86	13.2%
Distance from rostral border of orbit to caudal border of external naris	250	32	12.8%