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Rebbachisauridae is a clade of sauropod dinosaurs whose maximum diversification and abundance are known from the Cretaceous of South America. We describe an anterior caudal vertebra, MDPA-Pv 007, from the Upper Cretaceous of Argentine Patagonia, whose characters allow it to be referred to this clade. Also, two phylogenetic analyses reinforce the referral of the new material more exclusively to Rebbachisaurinae. We analyze pneumatic structures using the first CT scans of a caudal element of a rebbachisaurid. The excellent preservation of MDPA-Pv 007, combined with CT images, allows us to document external fossae and foramina that connect to larger internal chambers, constituting unambiguous evidence of pneumaticity. The centrum of MDPA-Pv 007 is camerate, with large interconnected internal chambers; this is accompanied by a neural arch with wide and deep fossae. Caudal pneumaticity has a complex phylogenetic distribution among neosauropods. This feature may have evolved independently in diplodocoids and titanosauriforms, or it could be ancestral for Neosauropoda but secondarily lost in a few lineages. Future investigations, taking advantage of new technologies, will provide insights into the phylogenetic distribution and paleobiological implications of pneumaticity in sauropod dinosaurs and other fossil archosaurs. [ABSTRACT FROM AUTHOR]

Pneumatic dorsal ribs are known for many sauropods, but to date costal pneumaticity has received relatively little attention. In particular, the pneumatic ribs of the holotype specimen of Brachiosaurus altithorax have been largely overlooked, although they present a unique configuration of pneumatic features. One rib, with a pneumatic foramen some distance down the shaft, was briefly described and illustrated in the early 20th century by Elmer S. Riggs. A second rib with a pneumatic foramen in the tuberculum of the rib has not previously been described or illustrated. This previously undescribed foramen is similar in location to those in some dorsal ribs of Brontosaurus excelsus and Giraffatitan brancai, but differs from them in both size and shape. The contrasting sites of costal pneumaticity in the holotype individual of Brachiosaurus altithorax emphasize the generally opportunistic mode of postcranial pneumatization, in both sauropods and other ornithodirans, but conform to models of pneumatization following vascularization. [ABSTRACT FROM AUTHOR]

The recurrent laryngeal nerve is an often cited example of "unintelligent design" in biology, especially in the giraffe. The nerve appears early in embryonic development, before the pharyngeal and aortic arches are separated by the development of the neck. The recurrent course of the nerve from the brain, around the great vessels, to the larynx, is shared by all extant tetrapods. Therefore we may infer that the recurrent laryngeal nerve was present in extinct tetrapods, had the same developmental origin, and followed the same course. The longest-necked animals of all time were the extinct sauropod dinosaurs, some of which had necks 14 meters long. In these animals, the neurons that comprised the recurrent laryngeal nerve were at least 28 meters long. Still longer neurons may have spanned the distance from the end of the tail to the brainstem, as in all extant vertebrates. In the longest sauropods these neurons may have been 40-50 meters long, probably the longest cells in the history of life. [ABSTRACT FROM AUTHOR]

Postcranial skeletal pneumaticity (PSP) is present in a range of basal sauropodomorphs spanning the basal sauropodomorph-sauropod transition. We describe the PSP of five taxa, Plateosaurus engelhardti, Eucnemesaurus fortis, Aardonyx celestae, Antetonitrus ingenipes, and an unnamed basal sauropod from Spion Kop, South Africa (hereafter referred to as the Spion Kop sauropod). The PSP of Plateosaurus is apparently sporadic in its occurrence and has only been observed in very few specimens, in which it is of very limited extent, affecting only the posterior cervical vertebrae and possibly the mid dorsals in one specimen. The PSP of Eucnemesaurus, Aardonyx, Antetonitrus, and the Spion Kop sauropod consists of subfossae (fossa-within-fossa structures) that excavate the vertices of the posterior infradiapophyseal fossae of the posterior dorsal vertebrae. These subfossae range from simple shallow depressions (Eucnemesaurus) to deep, steepsided, internally subdivided and asymmetrically developed chambers (Antetonitrus). The middle and anterior dorsal vertebrae of these taxa lack PSP, demonstrating that abdominal air sacs were the source of the invasive diverticula. The presence of pneumatic features within the infradiapophyseal fossae suggest that the homologous fossae of more basal saurischians and dinosauriforms were receptacles that housed pneumatic diverticula. We suggest that it is probable that rigid non-compliant lungs ventilated by compliant posterior air sacs evolved prior to the origination of Dinosauria. [ABSTRACT FROM AUTHOR]