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

Abstract

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 .

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

“…If we compare the present data of Brachiosaurus brancai with our own previously published data then the body surface estimations by photogrammetry are in the (Gunga et al 1995(Gunga et al , 1999. The main differences between the two reconstructions lie in the volume and mass estimations, i.e.…”

“…For the body mass estimation, here in contrast to the previous studies (Gunga et al 1995(Gunga et al , 1999, we assumed a tissue density of 0.8 kg per 1,000 cm 3 instead of 1.0 kg per 1,000 cm 3 . Finally, anatomical and physiological parameters were calculated after equations from Schmidt-Nielsen (1984), Anderson et al (1979), Calder (1984Calder ( , 1996 assuming a high metabolic rate comparable to mammals, and equating after Schmidt-Nielsen (1984) 1 l oxygen consumption during oxydative metabolism (at 0 C, 760 mm Hg) with 20,083 kJ.…”

“…A detailed description of the classical photogrammetrical method and the mathematical formulas which we applied can be omitted here because these procedures were described earlier (Gunga et al 1995(Gunga et al , 1999. Briefly, several pictures from the 3D reconstruction of the mounted skeleton of Brachiosaurus brancai were printed (Fig.…”

“…Therefore, it was the aim of the present study (1) to re-evaluate our own previously published data on the body and surface areas of the Late Jurassic Brachiosaurus brancai from Tendaguru/Tanzania (East Africa) (Gunga et al 1995(Gunga et al , 1999, mounted and exhibited at the Museum of Natural History (Berlin, Germany). Furthermore, we tested (2) whether the main organs of this extinct dinosaur such as skin, lung, heart, gastrointestinal tract, and muscular system, derived from the body mass and calculated according scaling equations, really fit into the anatomical dimensions of the thoracic and abdominal cavity of Brachiosaurus brancai if a slim body shape of this sauropod is assumed.…”

“…Therefore, we have introduced classical photogrammetry for assessing body mass and surface area of extinct organisms such as Brachiosaurus brancai Janensch, 1914(Gunga et al 1995. The highly disparate estimates to be found in the literature are mainly due to different methods for mass estimations, such as bone circumferences and models, and the main advantages and disadvantages of some of these methods have been intensively discussed before (Colbert 1962;Lambert 1980;Schmidt-Nielsen 1984Anderson et al 1985;Haubold 1990;Withers 1992;Carroll 1993;Gunga et al 1999;Henderson 1999;Seebacher 2001;Motani 2001;Christiansen & Fariµa 2004). However, recently it was pointed out that extensive postcranial skeletal pneumaticity in sauropods has to be taken in account, leading to a substantial mass reduction (Wedel 2003(Wedel , 2005.…”