Predicting Body Mass in Polar Bears: Is Morphometry Useful?

Cattet, Marc; Atkinson, Stephen N.; Polischuk, Susan C.

doi:10.2307/3802105

Cited by 26 publications

(27 citation statements)

References 21 publications

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“…Equations predicting body mass from morphological measurements are very variable in their precision. Equations for polar bears have r 2 values from 0.7 to 0.99 [28] and similar ranges are found for elephants [11,14,15]. The value for the Sumatran rhinoceros Dicerorhinus sumatrensis is a clear outlier.…”

Section: Discussionmentioning

confidence: 64%

Minimum convex hull mass estimations of complete mounted skeletons

et al. 2012

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Body mass is a critical parameter used to constrain biomechanical and physiological traits of organisms. Volumetric methods are becoming more common as techniques for estimating the body masses of fossil vertebrates. However, they are often accused of excessive subjective input when estimating the thickness of missing soft tissue. Here, we demonstrate an alternative approach where a minimum convex hull is derived mathematically from the point cloud generated by laser-scanning mounted skeletons. This has the advantage of requiring minimal user intervention and is thus more objective and far quicker. We test this method on 14 relatively large-bodied mammalian skeletons and demonstrate that it consistently underestimates body mass by 21 per cent with minimal scatter around the regression line. We therefore suggest that it is a robust method of estimating body mass where a mounted skeletal reconstruction is available and demonstrate its usage to predict the body mass of one of the largest, relatively complete sauropod dinosaurs: Giraffatitan brancai (previously Brachiosaurus ) as 23200 kg.

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Section: Discussionmentioning

confidence: 64%

Minimum convex hull mass estimations of complete mounted skeletons

et al. 2012

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“…For polar bears actively feeding on seals, it is likely that using morphometric measurements to estimate body mass is as accurate as determining mass directly from a scale unless stomach and gut content can be determined. The stomach capacity of a polar bear as a proportion of body mass would be within the 95% prediction interval that was 17% of body mass reported by Cattet et al (1997). Therefore, we conclude that estimation of body mass in polar bears using morphometric measurements is both accurate and precise enough for most population dynamic, monitoring, and behavioural studies.…”

Section: Discussionmentioning

confidence: 80%

Postnatal growth in body length and mass of polar bears (Ursus maritimus) at Svalbard

2002

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The von Bertalanffy curve was used to examine growth patterns in both body length and mass of female and male polar bears Ursus maritimus live-captured near Svalbard, Norway. A longer growth period in males resulted in pronounced sexual dimorphism in both body length and mass. Males were 1.16 times longer and 2.10 times heavier than females. The asymptotic body length of female and male polar bears from Svalbard was smaller than that for polar bears in four of six previously studied populations. Asymptotic body mass of females from Svalbard was lower than other previously studied populations, while males were generally lighter. The reasons for the lighter bears in Svalbard are unclear, but we believe they were not related to sampling error, ecosystem productivity, or genetic differences. The high pollution load of polar bears in Svalbard may have affected body size but this potential factor could not be assessed. The generally smaller size of polar bears in Svalbard was consistent with density-dependent growth effects but again, information on population density relative to carrying capacity was insuf®cient to assess this hypothesis.

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“…Measurement of size in large-bodied carnivores is problematic (Cattet et al 1997). Typically, body weight is used to estimate size in comparative studies; however, weight is highly variable in large species, changing with seasonal fluctuations in food, reproductive condition, and physical condition, among other factors (Gittleman 1986b).…”

Section: Comparative Analysesmentioning

confidence: 99%

Are Pinnipeds Functionally Different From Fissiped Carnivores? The Importance of Phylogenetic Comparative Analyses

Bininda‐Emonds

Gittleman

2000

Evolution

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It is widely assumed that adaptations to an aquatic lifestyle are so profound as to produce only obvious differences between pinnipeds and the remaining, largely terrestrial carnivore species ("fissipeds"). Thus, comparative studies of the order Carnivora routinely examine these groups independently. This approach is invalid for two reasons. First, fissipeds are a paraphyletic assemblage, which raises the general issue of when it is appropriate to ignore monophyly as a criterion for inclusion in comparative studies. Second, the claim that most functional characters (beyond a few undoubted characteristic features) are different in pinnipeds and fissipeds has never been quantitatively examined, nor with phylogenetic comparative methods. We test for possible differences between these two groups in relation to 20 morphological, life-history, physiological, and ecological variables. Comparisons employed the method of independent contrasts based on a complete and dated species-level phylogeny of the extant Carnivora. Pinnipeds differ from fissipeds only through evolutionary grade shifts in a limited number of life-history traits: litter weight (vs. gestation length), birth weight, and age of eyes opening (both vs. size). Otherwise, pinnipeds display the same rate of evolution as phylogenetically equivalent fissiped taxa for all variables. Overall functional differences between pinnipeds and fissipeds appear to have been overstated and may be no greater than those among major fissiped groups. Recognition of this fact should lead to a more complete understanding of carnivore biology as a whole through more unified comparative tests. Comparative studies that do not include monophyletic groups for phylogenetically based comparative tests should be reconsidered.

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Predicting Body Mass in Polar Bears: Is Morphometry Useful?

Cited by 26 publications

References 21 publications

Minimum convex hull mass estimations of complete mounted skeletons

Minimum convex hull mass estimations of complete mounted skeletons

Postnatal growth in body length and mass of polar bears (Ursus maritimus) at Svalbard

Are Pinnipeds Functionally Different From Fissiped Carnivores? The Importance of Phylogenetic Comparative Analyses

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