Landmarks and Semilandmarks - Geometric Morphometrics for Biologists - page 38

Landmark 6 lies at the posterior base of the fleshy adipose fin, where the fin meets the
skin of the dorsal midline. This point may be difficult to locate unambiguously because
it may be obscured by the fin overlapping the skin of the peduncle, so a pin is inserted to
mark its location for digitizing. In some of our studies we have attempted to use the ante-
rior insertion of the adipose fin, but its broadly curving profile in many species renders it
too difficult to repeat.
Note that landmarks 9

12 represent the ventral area of the body form, but they do not
capture the actual convex belly shape of these fishes. A great deal of effort was spent
in attempting to find appropriate landmark locations along the ventral profile, but no
repeatable and consistent landmarks were found that could be located on all piranha species.

Landmarks on the Skull of Sigmodon fulviventer
and Mus musculus domesticus
The landmarks on the skull of cotton rats, Sigmodon fulviventer ( Figure 2.10 ), were
selected to cover the skull as evenly as possible for the purpose of determining whether

FIGURE 2.10 Landmarks on the skull of cotton rats, Sigmodon
fulviventer and Mus musculus domesticus. (A) Landmarks used in
the initial analysis of S. fulviventer ( Zelditch et al., 1992, 1993 ;
Figure 2.11A ); (B) landmarks added for a comparative study of
S. fulviventer and M. m. domesticus; (C) landmarks used in the analysis
of M. m. domesticus.