Fig. 3. Concavity and convexity measurements of the carapace of a CT-scanned smooth trunkfish (17.0 cm total length, 12.3 cm carapace length) plotted as a function of percentage of carapace length. Maximum convexity (A) and concavity (C) are the maximum distances that the body extends and indents, respectively, relative to a segment connecting either the tips of the dorsal and ventro-lateral keels (S_L) (lateral measurements) or the tips of the two ventro-lateral keels (S_V) (ventral measurements). The location of maximum lateral convexity (B) is the distance from the dorsal keel to the point of maximum extension along the segment, S_L. The location of maximum lateral/ventral concavity (D) is the distance from the ventro-lateral keel to the point of maximum indentation along segments S_L (lateral) or S_V (ventral). Data on lateral maximum convexity and concavity are mean measurements of the two sides of the carapace. Data on ventral concavity are mean measurements of the two regions of ventral concavity found along S_V. In B the location of ventral maximum convexity occurs equidistant between ventro-lateral keels.