Open access (CC By) at PeerJ:
- Taylor, Michael P. 2014. Quantifying the effect of intervertebral cartilage on neutral posture in the necks of sauropod dinosaurs. PeerJ 2:e712. doi:10.7717/peerj.712 [PDF]
The full peer-review history is available.
An earlier version of this paper was made available as PeerJ Preprint, which at that point had not yet been peer-reviewed:
- Taylor, Michael P. 2014. Quantifying the effect of intervertebral cartilage on neutral posture in the necks of sauropod dinosaurs. PeerJ PrePrints 2:e588v1. doi:10.7287/peerj.preprints.588v1
Figure 1: Charles R. Knight’s famous 1897 painting of sauropods, which were then considered amphibious. In the foreground, Apatosaurus (“Brontosaurus” of his usage) wades in a lake, its neck erect. In the background, Diplodocus wanders on the shore, its neck held low and horizontal. These differences in posture may not represent different perceptions of the habitual behaviour of these different taxa, merely the postures these individuals happened to adopt at a particular moment.
Figure 2: Increased angle of elevation at an intervertebral joint when cartilage is included. Posterior cervical vertebrae 13 and 14 of Diplodocus carnegii holotype CM 84, from Hatcher (1901:plate III), in right lateral view. Top: C13 (yellow) in osteological neutral posture, with the condyle of C14 embedded in the cotyle of C13 and with zygapophyseal facets maximally overlapped. Bottom: intervertebral cartilage (black) added, and C13 (blue) rotated upwards to accommodate it. Since the zygapophyses remain maximally overlapped, a line between the centre of their facets forms the axis of rotation (white dot); red lines join the centre of rotation to the most anterior point of the bony condyle and of the intervertebral cartilage. By similarity, the angle between the yellow and blue vertebrae is equal to that between the red lines.
Figure 3: Close-up of area of rotation in Fig. 2. The two long lines, each of length h, connect the middle of the zygapophyseal facets to the anteriormost point of the condyle of the posterior vertebra and the cotyle of the anterior one. The short line of length t is projected at a right angle to the left line, and more or less connects the points on the condyle and cotyle. The angle between the two long lines is θ.
Figure 4: Effect of adding cartilage to the neutral pose of the neck of Apatosaurus louisae CM 3018. Images of vertebra from Gilmore (1936:plate XXIV). At the bottom, the vertebrae are composed in a horizontal posture. Superimposed, the same vertebrae are shown inclined by the additional extension angles indicated in Table 1. If the slightly sub-horizontal osteological neutral pose of Stevens and Parrish (1999) is correct, then the cartilaginous neutral pose would be correspondingly slightly lower than depicted here, but still much closer to the elevated posture than to horizontal. (Note that the posture shown here would not have been the habitual posture in life: see discussion.)
Figure 5: Effect of adding cartilage to the neutral pose of the neck of Diplodocus carnegii CM 84. Images of vertebra from Hatcher (1901:plate III). At the bottom, the vertebrae are composed in a horizontal posture. Superimposed, the same vertebrae are shown inclined by the additional extension angles indicated in Table 2.