Page 360 - Introduction to Paleobiology and The Fossil Record
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SPIRALIANS 2: MOLLUSKS 347
dorsal height of whorl peristome
impressed
area
whorl width test
outside umbilical seam
umbilical
diameter protoconch
growth lines
internal mould
body chamber
phragmocone
(a)
ventral lobe umbilical border
umbilical seam dorsal
dorso- lobe
1st lateral saddle 1st lateral lateral
lobe lobe
secondary
ventral dorso-
saddle umbilical lateral
saddle
saddle
(b) prong of ventral lobe
cadicone
sphaerocone platycone
serpenticone
ellipticone
oxycone
(c)
Figure 13.16 Morphology and shape terminology of the ammonoids: (a) external morphology,
(b) suture pattern, and (c) shell shapes.
