Wedel and Taylor (2013a: figure 9). Degree of neural spine bifurcation of presacral vertebrae in well-preserved Morrison Formation sauropod specimens representing several taxonomic groups. In all taxa with deep bifurcations, these are concentrated around the cervico-dorsal transition. ‘No data’ markers may mean that the vertebrae are not preserved (e.g., posterior dorsals of Suuwassea emilieae ANS 21122), that the degree of bifurcation cannot be assessed (e.g., anterior cervicals of Barosaurus lentus AMNH 6341), or that the serial positions of the vertebrae are uncertain so they contribute no information on serial changes in bifurcation (e.g., the four cervical vertebrae known for Barosaurus lentus YPM 429). The Camarasaurus specimens are roughly in ontogenetic order: C. lentus CM 11338 is a juvenile, C. grandis YPM 1905 and GMNH-PV 101/WPL 1995, and C. supremus AMNH 5761 are adults, and C. lewisi BYU 9047 is geriatric. See text for sources of data.

S9 Table. Postspinal lamina (POSL), serial variation in presacral vertebrae of Lacertini. Boxes represent the vertebrae in the column, including the atlas. Filled boxes indicate presence of the lamina in the respective vertebrae, whereas a dash stands for absence. Only the seven specimens with articulated vertebral column could be assessed.