Fig. 12. Deformations of the odontophore during swallowing. To provide an internal reference frame for the odontophore, all measurements were made after the anterior border of I6 had been rotated so that it was vertical. All lengths in A—D are mm plotted as a function of time (ms). The left panels show the changes in the antero-posterior length; the right panels show the changes in the dorso-ventral length. (A—D) Data from each of the four individual swallowing sequences; (E) these data normalized, averaged and smoothed ± 1 S.D. (F) Schematic diagrams indicating the antero-posterior odontophore length for frames 1, 9, 18 and 22. The anterior margin of the odontophore is highlighted with a gray line, and a parallel line drawn at the maximum antero-posterior length is highlighted with a black line. The dorso-ventral lengths of the odontophore for frames 1, 9, 18 and 22 are shown on the right. A gray line highlights the anterior margin of the odontophore, and a black line indicates the maximum length in the dorso-ventral direction perpendicular to this reference line. Compare original frames in Fig. 5. For definitions of periods t1, t2 and t4, see Materials and methods.