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Figure 3.4.
Facial landmarks plotted on the juvenile (left) and adult female (right)
skull of
Macaca fascicularis
(scale is approximate).
by increasing the sample size. When increasing the sample size is not
possible, we suggest the following alternate solution. Observe the land-
marks that lie in close proximity to one another on the form, and
decide on the basis of the scientific question under consideration and
your knowledge of the forms whether both landmarks are truly need-
ed for analysis. If both landmarks are important, the data can be
analyzed initially with only one of the two neighboring landmarks, and
then analyzed again with the other.
3.8.2 Crab-eating macaque facial skeleton
Three-dimensional landmark data from a sample of juvenile (N= 26)
and adult (N=30) male crab-eating macaque (
Macaca fascicularis
)
skulls provide the next example. Individual skulls were aged by
observing which teeth were present (Richtsmeier and Cheverud et al.,
1993). Developmental age groups were formed based on previous stud-
ies correlating tooth eruption with chronological ages in laboratory
specimens. The juvenile developmental age data set consists of indi-
viduals who had any combination of their deciduous teeth and first
permanent molar erupted. The adult developmental age data set con-
sists of individuals who have all permanent teeth in full eruption.
Data representing six landmarks on the right side of the facial
skeleton
(
Figure 3.4
)
of the crab-eating macaques were collected using
the 3Space tabletop digitizer (units are in
cm
). From these data, a mean
form matrix, a mean form, and a variance-covariance matrix were cal-
culated for each age group. These data are given in
Table 3.3a
-f
.
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