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Downsizing a giant: re-evaluating Dreadnoughtus body mass.

Bates KT, Falkingham PL, Macaulay S, Brassey C, Maidment SC - Biol. Lett. (2015)

Bottom Line: Estimates of body mass often represent the founding assumption on which biomechanical and macroevolutionary hypotheses are based.Similar results from a small sample of other archosaurs suggests that lower-end mass estimates derived from scaling equations are most plausible for Dreadnoughtus, based on existing volumetric and density data from extant animals.The relative and absolute discrepancies in mass predictions between volumetric models and scaling equations also indicate a need to systematically compare predictions across a wide size and taxonomic range to better inform studies of dinosaur body size.

View Article: PubMed Central - PubMed

Affiliation: Department of Musculoskeletal Biology, University of Liverpool, Duncan Building, Daulby Street, Liverpool L69 3GE, UK k.t.bates@liverpool.ac.uk.

ABSTRACT
Estimates of body mass often represent the founding assumption on which biomechanical and macroevolutionary hypotheses are based. Recently, a scaling equation was applied to a newly discovered titanosaurian sauropod dinosaur (Dreadnoughtus), yielding a 59 300 kg body mass estimate for this animal. Herein, we use a modelling approach to examine the plausibility of this mass estimate for Dreadnoughtus. We find that 59 300 kg for Dreadnoughtus is highly implausible and demonstrate that masses above 40 000 kg require high body densities and expansions of soft tissue volume outside the skeleton several times greater than found in living quadrupedal mammals. Similar results from a small sample of other archosaurs suggests that lower-end mass estimates derived from scaling equations are most plausible for Dreadnoughtus, based on existing volumetric and density data from extant animals. Although volumetric models appear to more tightly constrain dinosaur body mass, there remains a clear need to further support these models with more exhaustive data from living animals. The relative and absolute discrepancies in mass predictions between volumetric models and scaling equations also indicate a need to systematically compare predictions across a wide size and taxonomic range to better inform studies of dinosaur body size.

No MeSH data available.


Related in: MedlinePlus

Dreadnoughtus three-dimensional skeletal model and the (a) convex hull, (b) plus 21%, (c) maximal and (d) scaling equation mass volumetric reconstructions in lateral, oblique and aerial views. Black structures are respiratory volumes. (Online version in colour.)
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RSBL20150215F1: Dreadnoughtus three-dimensional skeletal model and the (a) convex hull, (b) plus 21%, (c) maximal and (d) scaling equation mass volumetric reconstructions in lateral, oblique and aerial views. Black structures are respiratory volumes. (Online version in colour.)

Mentions: A digital model of the Dreadnoughtus skeleton from Lacovara et al. [2] was used as a basis for a three-dimensional volumetric model (figure 1). For comparative purposes, we also modelled six extant taxa (three birds, two crocodilians and one lizard) and two other large sauropods using identical methods: Giraffatitan brancai, based on a laser scan of MB (Museum für Naturkunde, Berlin, Germany) SII from our previous study [5], and Apatosaurus louisae, based on a new three-dimensional model of CM (Carnegie Museum, USA) 3018 generated using photogrammetry [6]. Each three-dimensional skeletal model was posed in a standard ‘neutral’ posture, with the tail and neck extending horizontally and the limbs in a fully extended, vertical position (figure 1). Models were then divided into the following body segments: head, neck, ‘trunk’ (thorax and limb girdles), tail, thigh, shank, foot, humerus, forearm and hand.Figure 1.


Downsizing a giant: re-evaluating Dreadnoughtus body mass.

Bates KT, Falkingham PL, Macaulay S, Brassey C, Maidment SC - Biol. Lett. (2015)

Dreadnoughtus three-dimensional skeletal model and the (a) convex hull, (b) plus 21%, (c) maximal and (d) scaling equation mass volumetric reconstructions in lateral, oblique and aerial views. Black structures are respiratory volumes. (Online version in colour.)
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4528471&req=5

RSBL20150215F1: Dreadnoughtus three-dimensional skeletal model and the (a) convex hull, (b) plus 21%, (c) maximal and (d) scaling equation mass volumetric reconstructions in lateral, oblique and aerial views. Black structures are respiratory volumes. (Online version in colour.)
Mentions: A digital model of the Dreadnoughtus skeleton from Lacovara et al. [2] was used as a basis for a three-dimensional volumetric model (figure 1). For comparative purposes, we also modelled six extant taxa (three birds, two crocodilians and one lizard) and two other large sauropods using identical methods: Giraffatitan brancai, based on a laser scan of MB (Museum für Naturkunde, Berlin, Germany) SII from our previous study [5], and Apatosaurus louisae, based on a new three-dimensional model of CM (Carnegie Museum, USA) 3018 generated using photogrammetry [6]. Each three-dimensional skeletal model was posed in a standard ‘neutral’ posture, with the tail and neck extending horizontally and the limbs in a fully extended, vertical position (figure 1). Models were then divided into the following body segments: head, neck, ‘trunk’ (thorax and limb girdles), tail, thigh, shank, foot, humerus, forearm and hand.Figure 1.

Bottom Line: Estimates of body mass often represent the founding assumption on which biomechanical and macroevolutionary hypotheses are based.Similar results from a small sample of other archosaurs suggests that lower-end mass estimates derived from scaling equations are most plausible for Dreadnoughtus, based on existing volumetric and density data from extant animals.The relative and absolute discrepancies in mass predictions between volumetric models and scaling equations also indicate a need to systematically compare predictions across a wide size and taxonomic range to better inform studies of dinosaur body size.

View Article: PubMed Central - PubMed

Affiliation: Department of Musculoskeletal Biology, University of Liverpool, Duncan Building, Daulby Street, Liverpool L69 3GE, UK k.t.bates@liverpool.ac.uk.

ABSTRACT
Estimates of body mass often represent the founding assumption on which biomechanical and macroevolutionary hypotheses are based. Recently, a scaling equation was applied to a newly discovered titanosaurian sauropod dinosaur (Dreadnoughtus), yielding a 59 300 kg body mass estimate for this animal. Herein, we use a modelling approach to examine the plausibility of this mass estimate for Dreadnoughtus. We find that 59 300 kg for Dreadnoughtus is highly implausible and demonstrate that masses above 40 000 kg require high body densities and expansions of soft tissue volume outside the skeleton several times greater than found in living quadrupedal mammals. Similar results from a small sample of other archosaurs suggests that lower-end mass estimates derived from scaling equations are most plausible for Dreadnoughtus, based on existing volumetric and density data from extant animals. Although volumetric models appear to more tightly constrain dinosaur body mass, there remains a clear need to further support these models with more exhaustive data from living animals. The relative and absolute discrepancies in mass predictions between volumetric models and scaling equations also indicate a need to systematically compare predictions across a wide size and taxonomic range to better inform studies of dinosaur body size.

No MeSH data available.


Related in: MedlinePlus