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

Abstract

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. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Allometry of visceral organs in living amniotes and its implications for sauropod dinosaurs

“…Gunga et al (2008) had already concluded that the coelomic cavity of a 38 tonne sauropod dinosaur (Brachiosaurus brancai ), which they assumed to harbour a volume of 32 m 3 according to their body size reconstructions, provided more space than that necessary for most of the organs of this cavity (including a proportion of the skeleton, blood volume and muscle mass, but without accounting for mesenteries, coelomic fat and reproductive organs), which they estimated at 21 m 3 . Using our 'linear' approach and the reptile functions (table 2), and adopting a linear approach based on the mammal functions used by Gunga et al (2008) for those organs that we could not include in our study, we arrive at a volume estimate of only 17.6 m 3 . Evidently, even when considering that mesenteries, fat and reproductive organs are not included in these calculations, the present data allow for a dramatic increase in organ masses in the reconstruction of sauropod dinosaurs.…”

“…As sauropods are thought to have heterogeneous (avian-type) lungs with an air sac system ), a part of the space in the coelomic cavity was probably filled with these air sacs. In birds, the lungs and air sacs may account for as much as 20 per cent of the total body volume (King 1966); in the 38 tonne sauropod of Gunga et al (2008), with an estimated total volume of approximately 47.6 m 3 , this would represent a total lung and air sac volume of 9.5 m 3 . Even if we assume that the majority of this volume was placed within the coelomic cavity, the reconstruction would still allow for theoretical increases in any organ masses.…”

“…Assumptions were made for a medium-and a low-quality diet (with presumed apparent dry matter/energy digestibilities of 44 and 33%, respectively); additionally, we estimated the dry matter Table 2. Extrapolation of organ masses (in kg) of a hypothetical 38 000 kg vertebrate (the estimated mass of Brachiosaurus, a sauropod dinosaur; Gunga et al 2008) under different assumptions: 'linear approach', assuming linear scaling with BM for all clades, i.e. bZ1.0, using values for a from table 1; 'allometric approach', using the exact equations as given in table 1.…”

“…Table 3. Estimation of ingesta MRT in a hypothetical 38 000 kg vertebrate (the estimated mass of Brachiosaurus, a sauropod dinosaur; Gunga et al 2008) at different levels of metabolism and hence daily food intake (for 'medium'-and 'low'-quality food; Hummel et al 2008) at the extrapolated gut capacity of 610 kg dry matter (from table 1, linear approach, assuming a dry matter concentration of 15% in gut contents) and at a doubled gut capacity; MRT estimated according to Holleman & White (1989) …”

“…For example, Seymour & Lillywhite (2000) demonstrated in model calculations that an upright posture of the neck in sauropods is incompatible with the present understanding of cardiovascular function in vertebrates. Other examples for the use of allometry are the studies by Gunga et al (2007Gunga et al ( , 2008, who used allometric equations on the organ size of mammals from Anderson et al (1979), Schmidt-Nielsen (1984) and Calder (1996) to test whether reconstructions of the body size of a prosauropod and a sauropod (in particular, the volume of the coelomic cavity of these animals) match the calculated space requirement of the internal organs.…”