Neck Posture and Feeding Habits of Two Jurassic Sauropod Dinosaurs

Stevens, Kent A.; Parrish, J. Michael

doi:10.1126/science.284.5415.798

Cited by 171 publications

(307 citation statements)

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“…A more or less horizontal habitual neck posture has to be rejected. Z A m o d e l s. In the models used by Stevens & Parrish (1999, 2005a, 2005b) the facets of the preand postzygapophyses are aligned and centred, and simultaneously, the margins of "cotyle" and "condyle" of each intervertebral joint are parallel (Stevens & Parrish 2005a). In the extant mammals studied here, however, the margins of the intervertebral joints are not always parallel if the facets of the pre-and postzygapophyses are centred.…”

Section: Comparison Of the Results Obtained By Employing Different Mementioning

confidence: 99%

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

Christian

Dzemski

2007

Fossil Record

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The neck posture of Brachiosaurus brancai 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 Brachiosaurus brancai 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 Brachiosaurus brancai was a means for browsing in great heights as well as a means for increasing the feeding volume without moving the body.Schlü sselwö rter: Brachiosaurus, Sauropoden, Hals, Nahrungsaufnahme, Biomechanik, funktionelle Morphologie, Úkologie. ZusammenfassungDie Halsstellung von Brachiosaurus brancai Janensch, 1914 wird mit Hilfe der Preuschoft-Methode untersucht, die auf der Ermittlung der Spannungen in den Gelenken zwischen den Wirbelkö rpern entlang des Halses beruht. Verschiedene Rekonstruktionsmethoden langer Hä lse werden hinsichtlich ihrer Aussagekraft kritisch betrachtet, insbesondere die PreuschoftMethode sowie Ansä tze, die auf einer optimalen Gelenkung zwischen den Wirbeln beruhen. Die Ergebnisse untermauern die Zuverlä ssigkeit der Preuschoft-Methode, wä hrend Analysen an langen Hä lsen rezenter Wirbeltiere zeigen, dass Modelle mit optimaler Gelenkung sich weniger fü r die Rekonstruktion der habituellen Halsstellung wä hrend der Ruhe eignen. Stattdessen scheinen solche Modelle eher den Halsstellungen bei der Fortbewegung nahe zu kommen. Unter Einbeziehung verschiedener Methoden wird ein schlü ssiges Bild der Halsstellung und der Ernä hrungsstrategie von Brachiosaurus bran...

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Section: Comparison Of the Results Obtained By Employing Different Mementioning

confidence: 99%

“…The models proposed by Stevens and Parrish (1999, 2005a, 2005b are based on proper articulation between the neck vertebrae, especially in the zygapophyses. Such "zygapophyseal alignment" or "best-fit" postures tend to be comparatively low.…”

Section: Introductionmentioning

confidence: 99%

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

Christian

Dzemski

2007

Fossil Record

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“…The FEA also gives no hint about the posture of the neck in these sauropods (e.g. Christian 2002; Dzemski & Christian 2007;Sander et al 2009;Seymour 2009a,b;Stevens & Parrish 1999;Taylor et al 2009), although the absence of peak stresses in the vertebrae indicates that the test scenarios would have been possible for these sauropods at least occasionally. The horizontal neck position tested here represents a case in which higher stresses act on the vertebrae compared to a more vertical neck position (Taylor et al 2009).…”

Section: Discussionmentioning

confidence: 99%

Mechanical implications of pneumatic neck vertebrae in sauropod dinosaurs

et al. 2009

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The pre-sacral vertebrae of most sauropod dinosaurs were surrounded by interconnected, air-filled diverticula, penetrating into the bones and creating an intricate internal cavity system within the vertebrae. Computational finite-element models of two sauropod cervical vertebrae now demonstrate the mechanical reason for vertebral pneumaticity. The analyses show that the structure of the cervical vertebrae leads to an even distribution of all occurring stress fields along the vertebrae, concentrated mainly on their external surface and the vertebral laminae. The regions between vertebral laminae and the interior part of the vertebral body including thin bony struts and septa are mostly unloaded and pneumatic structures are positioned in these regions of minimal stress. The morphology of sauropod cervical vertebrae was influenced by strongly segmented axial neck muscles, which require only small attachment areas on each vertebra, and pneumatic epithelia that are able to resorb bone that is not mechanically loaded. The interaction of these soft tissues with the bony tissue of the vertebrae produced lightweight, air-filled vertebrae in which most stresses were borne by the external cortical bone. Cervical pneumaticity was therefore an important prerequisite for neck enlargement in sauropods. Thus, we expect that vertebral pneumaticity in other parts of the body to have a similar role in enabling gigantism.

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“…These results are important in view of the basic metabolic rate and the heat exchange of large organisms with their environment (Haubold 1990, Carroll 1993). We will return to this point when discussing the respiration and metabolism, because the heat reflected from the ground does not reach the large surface area of Brachiosaurus as it does the surface area of the tail and large hindlimbs in Dicraeosaurus and probably other giant sauropods (Stevens & Parrish 1999). Thermoregulatory mechanisms must take care of this problem.…”

Section: Gunga H Chr E T Al Body Size and Body Volume Of Tendagmentioning

confidence: 99%

Body size and body volume distribution in two sauropods from the Upper Jurassic of Tendaguru (Tanzania)

et al. 1999

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Allometric equations are often based on the body mass of an animal because body mass determines many physiological functions. This should also hold for Brachiosaurus brancai and Dicraeosaurus hansemanni, two sauropods from the Upper Jurassic of Tendaguru/Tanzania (East Africa) . Widely divergent estimates of body mass for the same specimen can be found in the literature for these two sauropods. Therefore, in order to determine the exact body mass and volume distribution in these sauropods, classical three-dimensional stereophotogrammetry as well as a newly developed laser scanner technique were applied to the mounted skeletons of Brachiosaurus brancai and Dicraeosaurus hansemanni in the Museum für Naturkunde (Berlin, Germany) . Thereafter, scaling equations were used to estimate the size of organ systems. In a second step it was tested whether the given data from photogrammetry could be brought in line with the results derived from the allometric equations. These findings are applied to possible ecological problems in the Upper Jurassic of Tendaguru/Tanzania .Key words: Dinosauria, Sauropoda, palaeophysiology, evolutionary physiology, palaeoecology, body mass estimations, metabolism, nutrition, gait and posture . ZusammenfassungDer Körpermasse eines Organismus werden oft allometrische Funktionen zugrunde gelegt, da von ihr viele physiologische Funktionen entscheidend abhängen . Dies sollte auch für ausgestorbene Organismen wie Brachiosaurus brancai und Dicraeosaurus hansemanni, zwei Sauropoden aus dem oberen Jura von Tendaguru/Tanzania in Ostafrika gelten. Da zu beiden Sauropoden nur sehr unterschiedliche Massenabschätzungen vorliegen, wurden die Körpermassen und Volumina von Brachiosaurus brancai und Dicraeosaurus hansemanni mit Hilfe der klassischen Photogrammetrie sowie einem neuentwickelten Laserscannerverfahren neu bestimmt. Basierend auf den so gemessenen Körpermassendaten wurden anschließend einige wichtige funktionell-morphologische Größen für eine paläophysiologische Rekonstruktion dieser Sauropoden mit Hilfe der Allometrie berechnet. Die gewonnenen Ergebnisse sind u . a. wichtig für die Rekonstruktion eines Ökosystems im oberen Jura von Ostafrika .

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Neck Posture and Feeding Habits of Two Jurassic Sauropod Dinosaurs

Cited by 171 publications

References 14 publications

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

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

Mechanical implications of pneumatic neck vertebrae in sauropod dinosaurs

Body size and body volume distribution in two sauropods from the Upper Jurassic of Tendaguru (Tanzania)

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