Giraffatitan Research Articles

The Tail of the Late Jurassic Sauropod Giraffatitan brancai: Digital Reconstruction of Its Epaxial and Hypaxial Musculature, and Implications for Tail Biomechanics

Dinosaur locomotion and biomechanics, especially of their pelvic girdles and hind limbs, have been analysed in numerous studies. However, detailed volumetric musculoskeletal models of their tails are rarely developed. Here, we present the first detailed three-dimensional volumetric reconstruction of the caudal epaxial and hypaxial musculature of the Late Jurassic sauropod Giraffatitan brancai, and highlight the importance and necessity of 3D modelling in musculoskeletal reconstructions. The tail of this basal macronarian is relatively short compared to diplodocids and other coexisting macronarians. The centre of mass lies well in front of the hind limbs, which support only ca. half the body weight. Still, our reconstruction suggests a total weight for the entire tail of ca. 2500 kg. We conclude that the hypaxial and hind limb muscles (more specifically the M. caudofemoralis longus and its counterpart the M. ilioischiocaudalis) in Giraffatitan were well developed and robustly built, compensating for the shorter length of the M. caufodemoralis longus, the main hind limb retractor muscle, in comparison with other sauropods. Our methodology allows a better-constrained reconstruction of muscle volumes and masses, in extinct taxa, and thus force and weight distributions, throughout the tail, than non-volumetric approaches.

The first confirmed sauropod dinosaur from Ethiopia discovered in the Upper Jurassic Mugher Mudstone

Ethiopia preserves extensive Mesozoic non-marine sedimentary sequences, but dinosaur fossils are exceptionally rare. The record is limited to a handful of theropod and ornithischian teeth from the Upper Jurassic Mugher Mudstone of the eastern margin of the Northwest Plateau, which has otherwise produced a diverse vertebrate fossil assemblage including actinopterygians, dipnoans, testudineans, crocodyliforms, and mammaliaforms. Here, we report the discovery of the first confirmed sauropod dinosaur from Ethiopia. The tooth BST VP-1/1 comes from a fine-to medium-grained, pebble and clast-rich zone with concentrated lenses of vertebrate microfossils in the lower part of the Mugher Mudstone. BST VP-1/1 is broad crowned, complete to the root, and slightly ellipsoidal midway in cross-section proximally toward the root. The distal half of the tooth has a chisel-like appearance. BST VP-1/1 is planar lingually, convex labially, and narrows apically. These features compare closely with those of early macronarians, such as Giraffatitan brancai from the penecontemporaneous Tendaguru Formation in Tanzania. This specimen demonstrates the presence of sauropods in Ethiopia for the first time, and indicates that macronarians were widespread in East Africa during the Late Jurassic Epoch.

The braincase of Malawisaurus dixeyi (Sauropoda: Titanosauria): A 3D reconstruction of the brain endocast and inner ear.

A braincase of the Cretaceous titanosaurian sauropod Malawisaurus dixeyi, complete except for the olfactory region, was CT scanned and a 3D rendering of the endocast and inner ear was generated. Cranial nerves appear in the same configuration as in other sauropods, including derived features that appear to characterize titanosaurians, specifically, an abducens nerve canal that passes lateral to the pituitary fossa rather than entering it. Furthermore, the hypoglossal nerve exits the skull via a single foramen, consistent with most titanosaurians, while other saurischians, including the basal titanosauriform, Giraffatitan, contain multiple rootlets. The size of the vestibular labyrinth is smaller than in Giraffatitan, but larger than in most derived titanosaurians. Similar to the condition found in Giraffatitan, the anterior semicircular canal is larger than the posterior semicircular canal. This contrasts with more derived titanosaurians that contain similarly sized anterior and posterior semicircular canals, congruent with the interpretation of Malawisaurus as a basal titanosaurian. Measurements of the humerus of Malawisaurus provide a body mass estimate of 4.7 metric tons. Comparison of body mass to radius of the semicircular canals of the vestibular labyrinth reveals that Malawisaurus fits the allometric relationship found in previous studies of extant mammals and Giraffatitan brancai. As in Giraffatitan, the anterior semicircular canal is significantly larger than is predicted by the allometric relationship suggesting greater sensitivity and slower movement of the head in the sagittal plane.

Three-Dimensional Musculoskeletal Modeling of the Sauropodomorph Hind Limb: The Effect of Postural Change on Muscle Leverage.

The biomechanical constraints for life at massive size can be directly observed in the evolutionary history of sauropodomorph dinosaurs. Members of this lineage underwent a number of major postural transitions as they increased in size from relatively small bipedal dinosaurs to massive titanosaurs that include the largest terrestrial animals of all time. To better understand the impact of gigantic size on the biomechanics of sauropods, we used three-dimensional musculoskeletal modeling to investigate how hind limb musculature was affected, first by the development of a quadrupedal stance from a bipedal one, and later in the transition from a narrow-gauge to a wide-gauge stance. Muscle moment arms were measured in four sauropodomorph taxa: the bipedal basal sauropodomorph Plateosaurus engelhardti, the narrow-gauge diplodocid Diplodocus carnegii, the titanosauriform Giraffatitan brancai, and the wide-gauge titanosaur Diamantinasaurus matildae. In Plateosaurus, low moment arm leverage in the hip extensors and knee flexors and extensors was observed suggesting high-velocity movement for fast locomotion. A reduction in hip extensor leverage in Diamantinasaurus was found which suggests a reduced role for the hind limb in forward propulsion in titanosaurs. An increase in overall hip adductor leverage and leverage of adductors 1 and 2 in Diamantinasaurus, compared with other taxa studied, might relate to the development of a wide-gauge stance. High knee flexor-extensor leverage in Giraffatitan but not Diamantinasaurus partially refutes the idea that broader femoral condyles in titanosauriforms increased knee torque production capabilities. Sauropodomorph postural changes clearly had an impact on the function and leverage of hind limb muscles. Anat Rec, 301:2145-2163, 2018. © 2018 Wiley Periodicals, Inc.

Disruptions and changing habits: The case of the Tendaguru expedition

ABSTRACTThis paper analyzes one of the biggest paleontological expeditions at the turn of the twentieth century. The Tendaguru expedition in the South of German East Africa, today’s Tanzania, took place from 1909 to 1913. Organised by Berlin’s Museum für Naturkunde, the expedition took advantage of the German colonial enterprise, unearthing and transporting over 225 tons of fossils to Berlin. Among them were the bones of what eventually became the biggest mounted dinosaur in the world: Brachiosaurus brancai. This paper focuses on the issues that interrupted or delayed the visible outcome of the Tendaguru expedition and thus complicated, delayed, or interrupted a supposedly very unproblematic enterprise. By focusing on these complications, this paper aims to give new insights into the history of the Tendaguru expedition and its aftermath. At the same time, this episode in the history of transforming natural objects into objects of natural history serves to show the ways in which disruptions shaped and transformed both paleontological fieldwork and practical work at the museum. Thereby, the paper ultimately calls attention to the complex interactions between disruptions, narratives, and object habits. It further illustrates how museum objects were shaped by misfortunes and adversity, as well as broader institutional, political, and scientific narrations in colonial and post-colonial Germany, thus continuing to reshape the object habits of Brachiosaurus brancai.

Can secondary osteons be used as ontogenetic indicators in sauropods? Extending the histological ontogenetic stages into senescence

AbstractSauropod bone histology has provided a great deal of insight into the life history of these enormous animals. However, because of high growth rates, annual growth rings are not common in sauropod long bones, so directly measuring growth rates and determining sexual maturity require alternative measures. Histological ontogenetic stages (HOS) have been established to describe the changes in bone histology through development for basal Macronaria and Diplodocoidea, and subsequently for Titanosauria. Despite this, the current HOS model is not able to discriminate bone tissues in late ontogeny, when sauropods had reached asymptotic size and continued to live into senescence but their long bones became extensively remodeled by secondary osteons and all primary bone was destroyed. Here we establish remodeling stages (RS) to characterize the Haversian bone development through ontogeny in eight sauropod taxa (Apatosaurinae,Giraffatitan brancai,Camarasaurusspp.,Dicraeosaurusspp.,Ampelosaurus atacis,Phuwiangosaurus sirindhornae,Magyarosaurus dacus, andAlamosaurus sanjuanensis) and find significant correlation of RS with corresponding femur length (CFL) for the studied taxa, with the exception ofDicraeosaurusandMagyarosaurus. Remodeling stages are based on the maximum number of observable generations of crosscutting osteons from the innermost, mid-, and outermost part of the cortex. The correlation with CFL indicates that secondary osteons present an ontogenetic signal that could extend the histological ontogenetic stages. Remodeling stages also provide additional insight into the changes in histology through ontogeny for Sauropoda. This method has the potential to be used in other taxa, such as thyreophorans and many ornithischians, that develop Haversian tissue through development.

“If the Americans can do it, so can we”: How dinosaur bones shaped German paleontology

Between 1909 and 1913, Berlin’s Museum für Naturkunde (Berlin Museum of Natural History) unearthed more than 225 tons of fossils in former German East Africa and transported them to Berlin. Among them were the bones of Brachiosaurus brancai, which would eventually become the biggest mounted dinosaur in the world. By analyzing the social and communicative strategies that made this expedition possible, this paper aims to reveal several aspects of natural history knowledge production at the end of the long nineteenth century. Using rhetoric, the director of the Geological–Paleontological Museum in Berlin, Wilhelm von Branca, conducted a highly successful campaign to market the dinosaurs in Prussia and to convince public opinion and the Prussian central state of the value of paleontology. He fired the Prussian imagination and took advantage of the competitive urge to emulate American paleontology and industry. This work examines how his public relations strategies shaped the German biological “landscape” of the first decades of the twentieth century. It asks: when and under what conditions did paleontology successfully appeal to the public? How does communication dictate, shape, and constrain the development of a specific epistemic agenda? And what kind of power do the public and money have?

Neurocranial Osteology and Neuroanatomy of a Late Cretaceous Titanosaurian Sauropod from Spain (Ampelosaurus sp.)

Titanosaurians were a flourishing group of sauropod dinosaurs during Cretaceous times. Fossils of titanosaurians have been found on all continents and their remains are abundant in a number of Late Cretaceous sites. Nonetheless, the cranial anatomy of titanosaurians is still very poorly known. The Spanish latest Cretaceous locality of “Lo Hueco” yielded a relatively well preserved, titanosaurian braincase, which shares a number of phylogenetically restricted characters with Ampelosaurus atacis from France such as a flat occipital region. However, it appears to differ from A. atacis in some traits such as the greater degree of dorsoventral compression and the presence of proatlas facets. The specimen is, therefore, provisionally identified as Ampelosaurus sp. It was CT scanned, and 3D renderings of the cranial endocast and inner-ear system were generated. Our investigation highlights that, although titanosaurs were derived sauropods with a successful evolutionary history, they present a remarkably modest level of paleoneurological organization. Compared with the condition in the basal titanosauriform Giraffatitan brancai, the labyrinth of Ampelosaurus sp. shows a reduced morphology. The latter feature is possibly related to a restricted range of head-turning movements.

Minimum convex hull mass estimations of complete mounted skeletons

Body mass is a critical parameter used to constrain biomechanical and physiological traits of organisms. Volumetric methods are becoming more common as techniques for estimating the body masses of fossil vertebrates. However, they are often accused of excessive subjective input when estimating the thickness of missing soft tissue. Here, we demonstrate an alternative approach where a minimum convex hull is derived mathematically from the point cloud generated by laser-scanning mounted skeletons. This has the advantage of requiring minimal user intervention and is thus more objective and far quicker. We test this method on 14 relatively large-bodied mammalian skeletons and demonstrate that it consistently underestimates body mass by 21 per cent with minimal scatter around the regression line. We therefore suggest that it is a robust method of estimating body mass where a mounted skeletal reconstruction is available and demonstrate its usage to predict the body mass of one of the largest, relatively complete sauropod dinosaurs: Giraffatitan brancai (previously Brachiosaurus) as 23200 kg.

Correction: A re-evaluation of Brachiosaurus altithorax Riggs, 1903 (Dinosauria, Sauropoda) and its generic separation from Giraffatitan brancai (Janensch, 1914)

Correction: A re-evaluation of Brachiosaurus altithorax Riggs, 1903 (Dinosauria, Sauropoda) and its generic separation from Giraffatitan brancai (Janensch, 1914)

A re-evaluation of Brachiosaurus altithorax Riggs 1903 (Dinosauria, Sauropoda) and its generic separation from Giraffatitan brancai (Janensch 1914)

ABSTRACT Although the macronarian sauropod Brachiosaurus is one of the most iconic dinosaurs, its popular image is based almost entirely on the referred African species Brachiosaurus brancai rather than the North American type species Brachiosaurus altithorax. Reconsideration of Janensch's referral of the African species to the American genus shows that it was based on only four synapomorphies and would not be considered a convincing argument today. Detailed study of the bones of both species show that they are distinguished by at least 26 characters of the dorsal and caudal vertebrae, coracoids, humeri, ilia, and femora, with the dorsal vertebrae being particularly different between the two species. These animals must therefore be considered generically separate, and the genus name Giraffatitan Paul 1988 must be used for “Brachiosaurus” brancai, in the combination Giraffatitan brancai. A phylogenetic analysis treating the two species as separate OTUs nevertheless recovers them as sister taxa in all most parsimonious trees, reaffirming a monophyletic Brachiosauridae, although only one additional step is required for Giraffatitan to clade among somphospondylians to the exclusion of Brachiosaurus. The American Brachiosaurus is shown to be somewhat different from Giraffatitan in overall bodily proportions: it had a longer and deeper trunk and probably a longer and taller tail, carried a greater proportion of its mass on the forelimbs, and may have had somewhat sprawled forelimbs. Even though it was overall a larger animal than the Giraffatitan lectotype, the Brachiosaurus holotype was probably immature, as its coracoids were not fused to its scapulae.

Synchrotron XRF analyses of element distribution in fossilized sauropod dinosaur bones

Sauropod dinosaurs were typically one magnitude larger than any other living or extinct terrestrial animal. This sheer size of the sauropod leads to scale effects in their biology and physiology that still are inadequately understood. The only remnants of the sauropods are their fossilized bones. These fossilized bones have sustained burial for some hundred million years and thus may have experienced significant diagenetic changes. These diagenetic changes often do not affect bone preservation on the histological level, but may lead to significant alterations of the bone microstructure. Here the influence of diagenesis on the microstructure of fossilized sauropod bones using femur cross section of Brachiosaurus brancai that was excavated in the Tendaguru beds in Tanzania is investigated. The element distribution in this dinosaur bone is studied by a combination of micro-X-ray-fluorescence (μ-XRF) using synchrotron radiation and energy dispersive X-ray analyses (EDX) in the scanning electron microscope. These techniques reveal quantitative values of the element concentration at a macroscopic level combined with qualitative information at high spatial resolution of the distribution of Ca, Co, Cr, V, Pb, U, Sr, Y, and As in the fossil bones. This allows a differentiation between the remnants of the original bone apatite and pore filling minerals and also a visualization of damage, e.g., cracks introduced by diagenetic processes.

A new body mass estimation ofBrachiosaurus brancaiJanensch, 1914 mounted and exhibited at the Museum of Natural History (Berlin, Germany)

Body mass and surface areas are important in several aspects for an organism living today. Therefore, mass and surface determinations for extinct dinosaurs could be important for paleo-biological aspects as well. Based on photogrammetrical measurement the body mass and body surface area of the Late Jurassic Brachiosaurus brancai Janensch, 1914 from Tendaguru (East Africa), a skeleton mounted and exhibited at the Museum of Natural History in Berlin (Germany), has been re-evaluated. We determined for a slim type of 3D reconstruction of Brachiosaurus brancai a total volume of 47.9 m3 which represents, assuming a mean tissue density of 0.8 kg per 1,000 cm3, a total body mass of 38,000 kg. The volume distributions from the head to the tail were as follows: 0.2 m3 for the head, neck 7.3 m3, fore limbs 2.9 m3, hind limbs 2.6 m3, thoracic-abdominal cavity 32.4 m3, tail 2.2 m3. The total body surface area was calculated to be 119.1 m2, specifically 1.5 m2 for the head, 26 m2 neck, fore limbs 18.8 m2, hind limbs 16.4 m2, 44.2 m2 thoracic-abdominal cavity, and finally the tail 12.2 m2. Finally, allometric equations were used to estimate presumable organ sizes of this extinct dinosaur and to test whether their dimensions really fit into the thoracic and abdominal cavity of Brachiosaurus brancai if a slim body shape of this sauropod is assumed. doi:10.1002/mmng.200700011

A new body mass estimation of <i>Brachiosaurus brancai</i> Janensch, 1914 mounted and exhibited at the Museum of Natural History (Berlin, Germany)

Body mass and surface areas are important in several aspects for an organism living today. Therefore, mass and surface determinations for extinct dinosaurs could be important for paleo-biological aspects as well. Based on photogrammetrical measurement the body mass and body surface area of the Late Jurassic <i>Brachiosaurus brancai</i> Janensch, 1914 from Tendaguru (East Africa), a skeleton mounted and exhibited at the Museum of Natural History in Berlin (Germany), has been re-evaluated. We determined for a slim type of 3D reconstruction of <i>Brachiosaurus brancai</i> a total volume of 47.9 m<sup>3</sup> which represents, assuming a mean tissue density of 0.8 kg per 1,000 cm<sup>3</sup>, a total body mass of 38,000 kg. The volume distributions from the head to the tail were as follows: 0.2 m<sup>3</sup> for the head, neck 7.3 m<sup>3</sup>, fore limbs 2.9 m<sup>3</sup>, hind limbs 2.6 m<sup>3</sup>, thoracic-abdominal cavity 32.4 m<sup>3</sup>, tail 2.2 m<sup>3</sup>. The total body surface area was calculated to be 119.1 m<sup>2</sup>, specifically 1.5 m<sup>2</sup> for the head, 26 m<sup>2</sup> neck, fore limbs 18.8 m<sup>2</sup>, hind limbs 16.4 m<sup>2</sup>, 44.2 m<sup>2</sup> thoracic-abdominal cavity, and finally the tail 12.2 m<sup>2</sup>. Finally, allometric equations were used to estimate presumable organ sizes of this extinct dinosaur and to test whether their dimensions really fit into the thoracic and abdominal cavity of <i>Brachiosaurus brancai</i> if a slim body shape of this sauropod is assumed. <br><br> doi:<a href="http://dx.doi.org/10.1002/mmng.200700011" target="_blank">10.1002/mmng.200700011</a>

Reconstruction of the cervical skeleton posture of <i>Brachiosaurus brancai</i> Janensch, 1914 by an analysis of the intervertebral stress along the neck and a comparison with the results of different approaches

The neck posture of <i>Brachiosaurus brancai</i> Janensch, 1914 is reanalysed by employing the Preuschoft method to deduce the pattern of stress in the joints between the vertebral centra along the neck. The cogency of different methods for reconstructing the posture of a long neck, especially the Preuschoft method and approaches that are based on optimal articulation of the neck vertebrae, is discussed critically. The results corroborate the reliability of the Preuschoft method whereas the analyses of recent vertebrates with long necks show that approaches based on optimal articulation of the neck vertebrae are less suited for reconstructing habitual postures of long necks during rest. Such models are better suited for reconstructing the neck posture that was employed during locomotion. With the evidence obtained by different methods a conclusive picture of the neck posture and the feeding strategy of <i>Brachiosaurus brancai</i> can be drawn. The neck appears to have been slightly S-shaped with a ventrally flexed cranial section, an approximately straight middle section, and a dorsally flexed proximal part. In the habitual posture during standing, the angle between the middle section of the neck and the horizontal plane was about 60° or 70°. During locomotion the whole neck probably was kept in an lower position with the inclination reduced by approximately 20° compared with the position at rest. During feeding movements of the head relative to the neck and movements in the cranial neck section were performed without much altering the height of the centre of gravity of the neck. With slow dorsoventral movements of the whole neck pronounced changes in the feeding height were possible. Sideways movements of the whole neck were performed by lateral flexion at the base of the neck. According to these findings, the long neck of <i>Brachiosaurus brancai</i> was a means for browsing in great heights as well as a means for increasing the feeding volume without moving the body. <br><br> Die Halsstellung von <i>Brachiosaurus brancai</i> Janensch, 1914 wird mit Hilfe der Preuschoft-Methode untersucht, die auf der Ermittlung der Spannungen in den Gelenken zwischen den Wirbelkörpern entlang des Halses beruht. Verschiedene Rekonstruktionsmethoden langer Hälse werden hinsichtlich ihrer Aussagekraft kritisch betrachtet, insbesondere die Preuschoft-Methode sowie Ansätze, die auf einer optimalen Gelenkung zwischen den Wirbeln beruhen. Die Ergebnisse untermauern die Zuverlässigkeit der Preuschoft-Methode, während Analysen an langen Hälsen rezenter Wirbeltiere zeigen, dass Modelle mit optimaler Gelenkung sich weniger für die Rekonstruktion der habituellen Halsstellung während der Ruhe eignen. Stattdessen scheinen solche Modelle eher den Halsstellungen bei der Fortbewegung nahe zu kommen. Unter Einbeziehung verschiedener Methoden wird ein schlüssiges Bild der Halsstellung und der Ernährungsstrategie von <i>Brachiosaurus brancai</i> gezeichnet. Der Hals wurde offenbar in einer leichten S-Form gehalten, mit einem ventralflektierten vorderen Halsabschnitt, einer etwa gerade gehaltenen Halsmitte und einer dorsalflektierten Halsbasis. In der habituellen Stellung des stehenden Tieres bildete die Halsmitte einen Winkel von etwa 60° oder 70° mit der Horizontalebene. Bei der Fortbewegung wurde der Hals vermutlich um rund 20° niedriger gehalten als in der Ruheposition. Während der Nahrungsaufnahme konnte der Kopf durch Bewegungen allein des vorderen Halsabschnittes positioniert werden, ohne dass dabei der Schwerpunkt des Halses wesentliche Höhenänderungen erfahren hätte. Langsame dorsoventrale Bewegungen des gesamten Halses ermöglichten auch erhebliche Änderungen der Kopfhöhe. Seitliche Bewegungen des gesamten Halses konnten an der Halsbasis erzeugt werden. Gemäß dieser Ergebnisse war der lange Hals von <i>Brachiosaurus brancai</i> sowohl ein Mittel zum Erreichen von Nahrungsquellen in großer Höhe als auch zur Vergrößerung des Volumens, das bei ruhendem Körper mit dem Kopf erreicht werden konnte. <br><br> doi:<a href="http://dx.doi.org/10.1002/mmng.200600017" target="_blank">10.1002/mmng.200600017</a>

Burly gaits: centers of mass, stability, and the trackways of sauropod dinosaurs

ABSTRACT The narrow- and wide-gauge trackways attributed to sauropod dinosaurs are hypothesized to be a consequence of the relative positions of their centers of mass. This hypothesis was tested using three-dimensional, trackway-producing computer models of two sauropods and studies of Asian elephants. Centers of mass of sauropod models were computed using density distributions that reflect the high degree of pneumatization of the skeletons and air sacs within the body. A close correspondence was found between the relative areas of hand and foot prints in different trackways and the relative fractions of the body weight borne by the forefeet and hindfeet in the different types of sauropods inferred to have made the trackways. Experimental studies of Asian elephants corroborated the close correspondence between relative areas of the hindfeet and forefeet and body weight distribution. Replicating actual sauropod trackways with the walking models enabled testing of proposed gaits for a sauropod model. Brachiosaurus brancai, with its more centrally positioned center of mass, was stable and possessed a wide safety margin only when replicating a wide trackway. Conversely, Diplodocus carnegii, with a more posteriorly placed center of mass, was most stable when replicating a narrow trackway. A trend for large sauropods (>12 tons), independent of clade, to have more anteriorly positioned centers of mass was identified, and it is proposed that all large sauropods were restricted to producing wide-gauge trackways for stability reasons. The primitive gait state for Sauropodomorpha was determined to be one that produced narrow-gauge tracways.

Texture analyses of Sauropod dinosaur bones from Tendaguru

The apatite texture of fossil Brachiosaurus brancai and Barosaurus africanus sauropod bones from the excavation site at Tendaguru, Tanzania, was characterized by neutron diffraction pole figures. The results obtained reveal predominantly 〈0 0 0 1〉-fibre textures of the apatite; the fibre direction coincides with the longitudinal direction of the long bones of the skeletons. Neutron pole figures further indicate that other texture types may also be present. Texture strength is similar to dinosaur tendons and contemporary turkey tendon studied by others. Variations of texture strength across the bone wall cross-sections are not significantly large.

Pneumatic structures in the cervical vertebrae of the Late Jurassic Tendaguru sauropods Brachiosaurus brancai and Dicraeosaurus

The presacral vertebrae of sauropod dinosaurs were surrounded and invaded by a complex system of pneumatic diverticula, which originated most probably from cervical air sacs connected with the respiratory apparatus. Cervical vertebrae of Brachiosaurus brancai and Dicraeosaurus sp., two sauropods from the Late Jurassic (?Oxfordian-Kimmerigian-Tithonian) eastern African locality Tendaguru, were examined with computed tomography to visualize internal pneumatic structures. With this method, comparative reconstructions of pneumatic diverticula in the neck of these sauropods were done that help to understand the biomechanical role of vertebral pneumaticity in sauropods. Internal pneumatic structures in Brachiosaurus brancai are semicamellate with few large camerae in the vertebral centrum, surrounded by pneumatic camellae. Dicraeosaurus exhibits a procamerate pneumatization pattern with few deep fossae penetrating to a broad median strut in the vertebra, but no internal pneumaticity was found. The semicamellate pneumatization pattern of Brachiosaurus brancai corresponds with another Late Jurassic Brachiosaurus specimen, whereas in Cretaceous brachiosaurid taxa like Sauroposeidon, the complexity of internal pneumatization increases to form a fully camellate pneumatization pattern. In Dicraeosaurus, internal pneumatization has most likely secondarily been reduced.

On the vestibular labyrinth of Brachiosaurus brancai

The extensive remains of large sauropods, excavated in the Upper Jurassic layers of the Tendaguru region of Tanzania, East Africa by Janensch [15], include an intact fossil cast of a vestibular labyrinth and an endocast of the large Brachiosaurus brancai. The approximately 150 million year old labyrinth cast demonstrates clearly a form and organisation congruent in detail to those of extant vertebrate species. Besides the near-orthogonal arrangement of semicircular canals (SCCs), the superior and inferior branches of the vestibulo-acoustic nerve, the endolymphatic duct, the oval and round windows, and the cochlea can be identified. The orientation of the labyrinth in the temporal bone is also equivalent to that of many extant vertebrates. Furthermore, the existence of the twelve cranial nerves can be identified from the endocast. The present study was initiated after the photogrammetric measurement of the skeleton volume of B. brancai [13] yielded a realistic estimate of body mass (74.42 metric tons). Dimensional analysis shows that body mass and average SCC dimensions of B. brancai generally fit with the allometric relationship found in previous studies of extant species. However, the anterior SCC is significantly larger than the allometric relationship would predict. This would indicate greater sensitivity, supporting the idea that the behavioural repertoire must have included much slower pitch movements of the head. These slower movements would most likely have involved flexion of the neck, rather than head pitching about the atlas joint. Pursuing the relationship between body mass and SCC dimensions further, the SCC frequency response is estimated by scaling up from the SCC dimensions of the rhesus monkey; this yields a range between 0.008-26 Hz, approximately one octave lower than for humans.

New Data on the Dimensions of Brachiosaurus brancai and Their Physiological Implications

New Data on the Dimensions of Brachiosaurus brancai and Their Physiological Implications