Ankylosis patterns in the postcranial skeleton and hyoid bones of the harbour porpoise (Phocoena phocoena) in the Baltic and North Sea

Abstract

The onset and timing of epiphyseal ankylosis in the vertebral column and flippers and ankylosis of the hyoid and sternal bones were studied in 350 skeletons of the harbour porpoise (Phocoena phocoena) originating from the Baltic and North Sea and held in the collections of the Zoological Museum (University of Copenhagen), the Museum of Natural History (Gothenburg), the National Museum of Natural History (Stockholm), and the German Oceanographic Museum (Stralsund). Epiphyseal ankylosis in the vertebral column started in the anterior cervical region and then initiated around the 23rd to 26th caudal vertebrae from where it proceeded in both directions. The progression of vertebral epiphyseal ankylosis eventually terminated in the thoracic and lumbar regions. Epiphyseal ankylosis in the flippers began at the distal end of the humerus and the proximal ends of the radius and ulna. The timing of ankylosis in the flippers was more consistent across the specimens than the timing of vertebral ankylosis. Males and females had similar timing of ankylosis in the vertebral column and the flippers. Complete fusion of the hyoid and sternal bones occurred within the first year of life in most specimens. The early development of the hyoid apparatus may be linked to use of suction in feeding.

Maturidade física da coluna vertebral de Tursiops truncatus (Cetacea) do sul do Brasil

“…During the Pattern 2, we noticed unclear differences between the sexes, however, the females UFSC 1281 and 1285 showed a more advanced stage of ontogenetic development than the two males UFSC 1126 and 1368 of almost the same age. Some authors suggest that in the second phase (Pattern 2) the trend of the Pattern 1 reverses itself and females subsequently begin to grow faster (Read et al, 1993;Galatius and Kinze, 2003). According to Read et al (1993), male and female Tursiops truncatus from Sarasota (U.S.A.) showed distinct patterns of growth and achieved different final body lengths.…”

“…The specimens were separated into patterns of column fusion based on the degree of fusion of the epiphyses to the vertebral body, as well as analysis of the G.L.G. The degree of epiphyseal fusion of the vertebral column was based on Galatius and Kinze (2003) (Figure 1): (A): no fusion -both epiphyseal plates free or not yet ossified; (B): initial fusion -at least one epiphyseal plate loosely fused to the centra; (C): progressing fusion -both epiphyseal plates fused to the centra, displaying clear sutures; (D): complete fusion -both epiphyseal plates fused to the centra, displaying no sutures. Specimens in the initial growth phase, i.e., with the entire vertebral column in degree A of epiphyseal fusion or with the beginning of epiphyseal fusion only on the cervical vertebrae, were considered calves in the broad sense (Pattern 1).…”

“…If all the epiphyses are fused to the vertebral body, the growth of the individual will cease and the animal can be considered physically mature (Mead and Potter, 1990;Rommel, 1990). Sexual maturity, on the other hand, varies with sex and geographic region (Wells and Scott, 1999) and usually occurs before physical maturity (Mead and Potter, 1990;Wells and Scott, 1999;Galatius and Kinze, 2003). On the east coast of the United States, Tursiops truncatus reaches physical maturity at approximately 13 years (Mead and Potter, 1990;1999).…”

Nipisat - a Saqqaq culture site in Sisimiut, central West Greenland (Vol. 331)

“…In the Danish population of porpoises all cervical vertebrae are fused in age group 6-7 years (females) and age group 10-13 years (males) (Galatius and Kinze 2003). A subadult, not yet sexually matured individual, was documented with a 63 mm long pelvic bone.…”

“…The fusion pattern of a large sample of Danish harbour porpoises showed that fusion starts in the cervical region and proceeds from both ends terminating in the thoracic region, and physical maturity, i.e. complete fusion of all vertebrae is achieved very late in an individuals life (Galatius and Kinze 2003).…”