Osteologically Neutral Pose (ONP) and maximum dorsoventral excursions at the intervertebral joints along the neck and at the neck-trunk transition of <i>Mamenchisaurus youngi</i>.

The angles are relative to a straight line of the middle axes of the vertebral centra. Positive angles mean dorsiflexion. For most joints in the midsection of the neck the ONP is straight. c1–c18, cervical vertebrae, d1,d2, first two dorsal vertebrae. An error of up to 5 degrees has to be taken into account for all angles due to deformations of the vertebrae and uncertainties in the estimate of the thickness of the intervertebral cartilage.