Downsizing a giant: re-evaluating Dreadnoughtus body mass
File(s)
Author(s)
Bates, KT
Falkingham, PL
Macaulay, S
Brassey, C
Maidment, SCR
Type
Journal Article
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.
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.
Date Issued
2015-06-01
Date Acceptance
2015-05-18
Citation
Biology Letters, 2015, 11 (6)
ISSN
1744-957X
Publisher
Royal Society, The
Journal / Book Title
Biology Letters
Volume
11
Issue
6
Copyright Statement
© 2015 The Authors. Published by the Royal Society under the terms of the Creative Commons Attribution
License http://creativecommons.org/licenses/by/4.0/, which permits unrestricted use, provided the original
author and source are credited.
License http://creativecommons.org/licenses/by/4.0/, which permits unrestricted use, provided the original
author and source are credited.
License URL
Subjects
Science & Technology
Life Sciences & Biomedicine
Biology
Ecology
Evolutionary Biology
Life Sciences & Biomedicine - Other Topics
Environmental Sciences & Ecology
Dreadnoughtus
body mass
modelling
scaling equations
SAUROPOD DINOSAUR
Publication Status
Published
Article Number
20150215