52
Biology of Sea Turtles, Vol. II
2.3.2 AXIAL SKELETON
Like all turtles, sea turtles have eight cervical vertebrae, with the atlas (C1) articulating
with the skull and the C8 cervical vertebra attaching to the carapace. There are 10
dorsal (or trunk) vertebrae, 2–3 sacral vertebrae, and 12 or more caudal vertebrae
(Figure 2.7). The first cervical vertebra (the atlas) is a three-part bone, which articulates
with the occipital condyle at the posterior of the skull. Posteriorly, the atlas articulates
with the axis. Next are three similarly shaped, opisthocoelous vertebrae with convex
centra or vertebral bodies anteriorly and concave centra posteriorly. Cervical vertebrae
6 and 7 articulate with one another via flat-faced centra (Pritchard, personal communication) and are occasionally fused (Zangerl et al., 1988). The eighth cervical vertebra
FIGURE 2.11 A cheloniid skull in dorsal (A) and ventral (B) views. The external bones of
the splanchnocranium and neurocranium are identified. (Adapted from Wyneken, J. The
Anatomy of Sea Turtles, U.S. Department of Commerce, NOAA Technical Memorandum
NMFS-SEFSC-470, 2001. With permission.)
1123_C02.fm Page 52 Friday, November 15, 2002 11:16 AM
Biology of Sea Turtles, Vol. II
2.3.2 AXIAL SKELETON
Like all turtles, sea turtles have eight cervical vertebrae, with the atlas (C1) articulating
with the skull and the C8 cervical vertebra attaching to the carapace. There are 10
dorsal (or trunk) vertebrae, 2–3 sacral vertebrae, and 12 or more caudal vertebrae
(Figure 2.7). The first cervical vertebra (the atlas) is a three-part bone, which articulates
with the occipital condyle at the posterior of the skull. Posteriorly, the atlas articulates
with the axis. Next are three similarly shaped, opisthocoelous vertebrae with convex
centra or vertebral bodies anteriorly and concave centra posteriorly. Cervical vertebrae
6 and 7 articulate with one another via flat-faced centra (Pritchard, personal communication) and are occasionally fused (Zangerl et al., 1988). The eighth cervical vertebra
FIGURE 2.11 A cheloniid skull in dorsal (A) and ventral (B) views. The external bones of
the splanchnocranium and neurocranium are identified. (Adapted from Wyneken, J. The
Anatomy of Sea Turtles, U.S. Department of Commerce, NOAA Technical Memorandum
NMFS-SEFSC-470, 2001. With permission.)
1123_C02.fm Page 52 Friday, November 15, 2002 11:16 AM