Proc. Natl. Acad. Sci. (USA) 107(44): 18903-18908. 4 figs. Nov. 2, 2010.

–P. 18906: {"Short-necked sloths (C[holoepus]. hoffmanni) possess five to six ribless neck vertebrae. Manatees are known to typically possess six ribless neck vertebrae [Buchholtz et al., 2007]. We predict that when data on their axial skeleton ossification sequences are available, they will show one to two cranial-most rib-bearing vertebrae that are developmentally cervical. That is, they will exhibit late ossification of their centra, after that of more distal, rib-bearing vertebrae and coincident with more proximal cervical vertebrae."}