Caudal pneumaticity varies among sauropods.

<p>In the diplodocid <i>Tornieria</i>, the first 15–20 caudal vertebrae have neural arch laminae and fossae, and lateral pneumatic foramina opening into large internal chambers. Images traced from Remes (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0078213#pone.0078213-Remes1" target="_blank">[51]</a>: fig. 31 [lateral view]) and Janensch (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0078213#pone.0078213-Janensch4" target="_blank">[72]</a>: fig. 7 [cross-section]); the two views are from different vertebrae. In the basal titanosaurian <i>Malawisaurus</i>, caudal pneumaticity is restricted to a handful of proximal caudal vertebrae, in which the neural arches are honeycombed with pneumatic chambers but the vertebral centra are solid. Images traced from Wedel (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0078213#pone.0078213-Wedel4" target="_blank">[12]</a>: fig. 2A [lateral view] and 2C [cross-section]). In the derived titanosaurian <i>Saltasaurus</i>, the first 20–25 caudal vertebrae have large external fossae but small external foramina, and both the neural arches and centra are honeycombed with chambers. Images traced from Powell (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0078213#pone.0078213-Powell1" target="_blank">[59]</a>: plate 53 [lateral view]) and Cerda <i>et al</i> <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0078213#pone.0078213-Cerda1" target="_blank">[20]</a>: fig. 4F [cross-section]); the two views are from different vertebrae.