Postnatal ossification of the thoracic limb in striped dolphins (Stenella coeruleoalba) (Meyen, 1833) from the Mediterranean Sea

We analyzed the thoracic limbs of 24 striped dolphins, Stenella coeruleoalba, by means of X-ray techniques. The body length of the dolphins, the number of postnatal dentine growth layers in the teeth, the degree of ossification of the hyoid bones, and development of the gonads (when available) were correlated with X-rays and used to estimate growth stages and skeletal maturity. Newborn animals showed advanced ossification centers in the humerus and at the proximal end of the radius and ulna. The proximal end of the humerus and the distal end of the radius and ulna ossify later, followed by closure of the epiphyseal plates at the proximal and distal ends of the metacarpal bones and phalanges. We identified physical maturity by epiphyseal fusion in the thoracic limb, and considered full maturity to have been attained with deposition of bone at the level of the epiphysis-metaphysis line. The results are discussed in relation to a possible new system of age determination in S. coeruleoalba.