. The Canadian field-naturalist. . '1&) T^ 2B0 220 240 Body length (cm) iS iS" Figure 8. Relationship between the degree of fusion in the flippers and body length in male White-beaked Dolphins (Lagenorhynchus albirostris). The bones in the flippers are labelled as follows: (a) humerus; (b) radius; (c) ulna; (d) phalange I. Morphometric Measurements and Estimated Ages Measurements taken from the ice-entrapped dol- phins are presented in Tables 4 and 5. Longitudinal tooth sections provided the most reliable means of estimating age (Tables 4 and 5). A narrow layer of uniform dentine in t
. The Canadian field-naturalist. . '1&) T^ 2B0 220 240 Body length (cm) iS iS" Figure 8. Relationship between the degree of fusion in the flippers and body length in male White-beaked Dolphins (Lagenorhynchus albirostris). The bones in the flippers are labelled as follows: (a) humerus; (b) radius; (c) ulna; (d) phalange I. Morphometric Measurements and Estimated Ages Measurements taken from the ice-entrapped dol- phins are presented in Tables 4 and 5. Longitudinal tooth sections provided the most reliable means of estimating age (Tables 4 and 5). A narrow layer of uniform dentine in the section ended in a distinct clear line; this was identified as the neonatal line (GLG). The first postnatal GLG was wider than sub- sequent layers which were regularly spaced but declined in width toward the pulp cavity. Between 15-17 GLGs were found in the teeth before the pulp cavity was filled; these layers were more difficult to "read". GLGs beyond the first postnatal layer were assumed to be deposited annually. The ice-entrapped dolphins at Port-aux-Basques were primarily young animals with lengths ranging from 189-241 cm (n = 31, mean length = 213 cm, = 11 cm) and estimated ages from two to seven years (n = 34, mean age = years, = years). Most of the dolphins were two to three years of age. The group of dolphins entrapped at Point Verde ranged in length from 168 to 305 cm (n = 37, mean length = 229 cm, = 39 cm). Thirteen of the Point Verde animals were one year old; the remain- ing fifteen were adults more than six years old (n = 15, mean age = years, = years). The dolphins grew quickly prior to three years of age (Figures 4 and 5). Males showed a different growth pattern from females in that they grew at a faster rate and tended to be larger than females after reaching about three years of age. Morphometric data for the two sites were combined and non-linear regressions between age and length were performed for both sexes
Size: 1936px × 1291px
Photo credit: © Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorottawafi, bookcentury1900, bookdecade1910, bookyear1919
