FIGURE 1 in Use of scalation landmarks in geometric morphometrics of squamate reptiles: a comment on homology

FIGURE 1. Diagrams of specimens of the Crotalus viridis complex with 14 (A) and 16 (B) supralabial scales, respectively (supralabial scale rows are shaded in grey). For (A), the red dot marks a fixed landmark at the center of the series, seven scales from the first and seven scales from the last supralabial scale. Placing a corresponding fixed landmark on specimen B requires that one choose between seven scales from the first supralabial, seven scales from the last supralabial, or the suture at the center of the series, providing three mutually exclusive options (red dots). Selecting any of these options changes the topological position of the landmark relative to the first, the last, or both of these scales in the series. Fixed landmarks applied to scale rows variable in count renders secondary homology intractable, regardless of whether scales are counted from a consistent anchor point.