Limits...
An advanced shape-fitting algorithm applied to quadrupedal mammals: improving volumetric mass estimates.

Brassey CA, Gardiner JD - R Soc Open Sci (2015)

Bottom Line: Generating reliable estimates for body mass is therefore a necessary step in many palaeontological studies.We fit α-shapes to three-dimensional models of extant mammals and calculate volumes, which are regressed against mass to generate predictive equations.Our optimal model is characterized by a high correlation coefficient and mean square error (r (2)=0.975, m.s.e.=0.025).

View Article: PubMed Central - PubMed

Affiliation: Faculty of Life Sciences , University of Manchester , Manchester M13 9PL, UK.

ABSTRACT
Body mass is a fundamental physical property of an individual and has enormous bearing upon ecology and physiology. Generating reliable estimates for body mass is therefore a necessary step in many palaeontological studies. Whilst early reconstructions of mass in extinct species relied upon isolated skeletal elements, volumetric techniques are increasingly applied to fossils when skeletal completeness allows. We apply a new 'alpha shapes' (α-shapes) algorithm to volumetric mass estimation in quadrupedal mammals. α-shapes are defined by: (i) the underlying skeletal structure to which they are fitted; and (ii) the value α, determining the refinement of fit. For a given skeleton, a range of α-shapes may be fitted around the individual, spanning from very coarse to very fine. We fit α-shapes to three-dimensional models of extant mammals and calculate volumes, which are regressed against mass to generate predictive equations. Our optimal model is characterized by a high correlation coefficient and mean square error (r (2)=0.975, m.s.e.=0.025). When applied to the woolly mammoth (Mammuthus primigenius) and giant ground sloth (Megatherium americanum), we reconstruct masses of 3635 and 3706 kg, respectively. We consider α-shapes an improvement upon previous techniques as resulting volumes are less sensitive to uncertainties in skeletal reconstructions, and do not require manual separation of body segments from skeletons.

No MeSH data available.


Related in: MedlinePlus

(a) Mammoth (Ma. primigenius) and (b) sloth (Me. americanum) α-shapes illustrating the fit achieved when refinement coefficient k=0.4274 (number of points=500 000). At this refinement coefficient, α-shapes join the right and left appendages within the fore- and hindlimbs, while leaving the forelimbs separate from the hind limbs. The skull of Me. americanum is also joined to the fore limbs.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4555864&req=5

RSOS150302F5: (a) Mammoth (Ma. primigenius) and (b) sloth (Me. americanum) α-shapes illustrating the fit achieved when refinement coefficient k=0.4274 (number of points=500 000). At this refinement coefficient, α-shapes join the right and left appendages within the fore- and hindlimbs, while leaving the forelimbs separate from the hind limbs. The skull of Me. americanum is also joined to the fore limbs.

Mentions: Calculated values for αvol and associated body mass estimates for Ma. primigenius and Me. americanum are given in table 3. Based on the densest point cloud dataset, the woolly mammoth (Ma. primigenius) is estimated to have weighed 3635 kg, and the ground sloth (Me. americanum) is reconstructed as weighing 3706 kg (figure 5).Figure 5.


An advanced shape-fitting algorithm applied to quadrupedal mammals: improving volumetric mass estimates.

Brassey CA, Gardiner JD - R Soc Open Sci (2015)

(a) Mammoth (Ma. primigenius) and (b) sloth (Me. americanum) α-shapes illustrating the fit achieved when refinement coefficient k=0.4274 (number of points=500 000). At this refinement coefficient, α-shapes join the right and left appendages within the fore- and hindlimbs, while leaving the forelimbs separate from the hind limbs. The skull of Me. americanum is also joined to the fore limbs.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4555864&req=5

RSOS150302F5: (a) Mammoth (Ma. primigenius) and (b) sloth (Me. americanum) α-shapes illustrating the fit achieved when refinement coefficient k=0.4274 (number of points=500 000). At this refinement coefficient, α-shapes join the right and left appendages within the fore- and hindlimbs, while leaving the forelimbs separate from the hind limbs. The skull of Me. americanum is also joined to the fore limbs.
Mentions: Calculated values for αvol and associated body mass estimates for Ma. primigenius and Me. americanum are given in table 3. Based on the densest point cloud dataset, the woolly mammoth (Ma. primigenius) is estimated to have weighed 3635 kg, and the ground sloth (Me. americanum) is reconstructed as weighing 3706 kg (figure 5).Figure 5.

Bottom Line: Generating reliable estimates for body mass is therefore a necessary step in many palaeontological studies.We fit α-shapes to three-dimensional models of extant mammals and calculate volumes, which are regressed against mass to generate predictive equations.Our optimal model is characterized by a high correlation coefficient and mean square error (r (2)=0.975, m.s.e.=0.025).

View Article: PubMed Central - PubMed

Affiliation: Faculty of Life Sciences , University of Manchester , Manchester M13 9PL, UK.

ABSTRACT
Body mass is a fundamental physical property of an individual and has enormous bearing upon ecology and physiology. Generating reliable estimates for body mass is therefore a necessary step in many palaeontological studies. Whilst early reconstructions of mass in extinct species relied upon isolated skeletal elements, volumetric techniques are increasingly applied to fossils when skeletal completeness allows. We apply a new 'alpha shapes' (α-shapes) algorithm to volumetric mass estimation in quadrupedal mammals. α-shapes are defined by: (i) the underlying skeletal structure to which they are fitted; and (ii) the value α, determining the refinement of fit. For a given skeleton, a range of α-shapes may be fitted around the individual, spanning from very coarse to very fine. We fit α-shapes to three-dimensional models of extant mammals and calculate volumes, which are regressed against mass to generate predictive equations. Our optimal model is characterized by a high correlation coefficient and mean square error (r (2)=0.975, m.s.e.=0.025). When applied to the woolly mammoth (Mammuthus primigenius) and giant ground sloth (Megatherium americanum), we reconstruct masses of 3635 and 3706 kg, respectively. We consider α-shapes an improvement upon previous techniques as resulting volumes are less sensitive to uncertainties in skeletal reconstructions, and do not require manual separation of body segments from skeletons.

No MeSH data available.


Related in: MedlinePlus