Comparative dental development and microstructure of ... - UCL

196 A. D. BEYNON ET AL.
Figure 16. Striae of Retzius in the cervical region of P. nyanzae and C. apella. InProconsul the striae
approach 80–90 degrees to the EDJ. In Cebus they are reminiscent of P. boisei and are aligned at a much
reduced inclination to the EDJ. Neither tooth size, body size or enamel thickness therefore, account for
these contrasting stria angles.
good evidence to regard Proconsul as having
thin enamel with respect to other primates
of similar body mass or similar dentine cap
area.
Regardless of what exactly is defined as
‘‘thin’’ or ‘‘thick’’, the enamel in Proconsul
from Rusinga Island appears to be thicker
than that reported for Proconsul from other
early Miocene sites. This may not be surprising
in retrospect given the evidence that
Rusinga and Mfangano Island sites were
most similar to dry seasonal forest environments
and also had more open conditions
than the tropical, non-seasonal, wet evergreen
forest faunas reported for Songhor
and Koru (Andrews, 1996). Although this is
not direct evidence for any differences in
diet between the different species of Proconsul
the cumulative evidence available so far
suggests there might well have been.
Enamel and dentine morphology
Striae in Proconsul enamel form high angles
to the EDJ especially in the cervical portion
of the lateral enamel. Figure 16 demonstrates
the contrast in striae angles at the
cervix of a thick enamelled M 2 of C. apella
with those in the M 2 of P. nyanzae (RU
1695). The striae in Cebus resemble those
reported in robust australopithecines
(Beynon & Wood, 1986; Grine & Martin,
1988). This comparison suggests that tooth
size, enamel thickness and body size are not
likely to be factors that influence cervical
stria angulation in primate teeth. In general,
the highest mean values for cervical striae