Preliminary ontogeny of the giraffe neck.

The giraffe juvenile has different proportions of head to neck from the adult. The head just about doubles in size from the juvenile to adult, whereas the neck increases almost 4.5× (roughly four times) in length. The T1 posterior dorsal vertebral width of the newborn is clearly wider than in the adult where it is narrow. In the okapi, the dorsal vertebral width is narrow in both juvenile and adult. The giraffe neck changes in ontogeny anisometrically. In the okapi the changes are more isometric. The giraffe juvenile vertebrae are shorter and do not have fused the cranial epiphyseal plates. That facilitates anterior elongation-growth. The ventral tubercles are undeveloped. The juvenile T1 is wide caudally unlike the adult. This may be a similarity to a gelocid (Gelocidae) ancestor of the giraffe.