FLIPPER DEVELOPMENT IN THE MEDITERRANEAN STRIPED DOLPHIN (STENELLA-COERULEOALBA)

Background: Studies of population biology are scarce in Mediterranean striped dolphins (Stenella coeruleoalba) mostly because of the lack of samples. Until now, studies of physical maturity, growth, and develop ment of the flipper bones were not available for this species in the M editerranean. Methods: The osteological features and metric characters of the pectoral limbs of Mediterranean striped dolpins were analyzed with radiological techniques. Measurements were made directly on the r adiographic films. Results and Conclusions: We found five carpal bones arranged in a proximal row of three and a distal row of two, although one or two additional osseous elements were occasionally observed. Th e phalangeal formula (excluding metacarpals) was established as 1-2:8- 9-10:6-5-7:3-2:1-2. In metacarpals, epiphyseal ossification centers ma tured at the same time at both ends. As a general rule, the ossificati on of the epiphyses in the flipper bones showed a decreasing gradient in the proximodistal direction, confirming the pattern previously desc ribed in other species. Phalangeal epiphyses were not useful as indica tors of skeletal maturity, and grading epiphyseal maturation of the di stal radius and ulna is proposed as the more straightforward and preci se method for assessing bone maturation, In females, maturity of the f lipper was achieved between 5 and 6 years of age and 160-175 cm of bod y length, whereas this maturation occurred between 8 and 9 years of ag e and 170-181 cm in length in males. Prediction of gender through exam ination of flipper structure was not feasible. (C) 1996 Wiley-Liss, In c.