Skeletal development of the striped dolphin (Stenella coeruleoalba) in Japanese waters.

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Development, sexual dimorphisms and individual differences of the skeleton of the striped dolphin (<I>Stenella coeruleoalba</I>) living off the Pacific coast of Japan were examined. As materials, 38 individuals were used. Cranial skeleton reach adult plateau at the age of 3. Earbone increases little after birth. Most of postcranial skeleton reach adult size at the age of 7-10. Length of thoracic and lumbar vertebrae, thylohyals, stylohyals, ribs and sternals continue to grow at the age of 15-19. Length of the 2nd-the 7th cervical vertebrae reach adult plateau at the age of 3. The front edge of the occipital in adult female overhangs the frontals to form a crest, but in adult males the crest is typically absent. Width of rostrum (except for at base) and length of basyhyal, the 2nd-8th ribs and pelvic bones are larger in male on average than in female. Individual differences are found in the number of vertebrae (77-81), chevron bones (26-31), phalanges of the 1st digit (3-4), the 2nd (5-8), the 3rd (7-10) and the 4th (2-3), teeth in upper left (43-52), upper right (43-52), lower left (41-50) and lower right (42-53) . The species reaches physical maturity at ages between 15 and 19.
日本哺乳類学会の論文