This page serves supplemental imagery for a paper entitled Comparative finite element analysis of the cranial performance of four herbivorous marsupials by A.C. Sharp (In press, Journal of Morphology). The abstract is as follows:
Marsupial herbivores exhibit a wide variety
of skull shapes and sizes to exploit different ecological
niches. Several studies on teeth, dentaries, and jaw
adductor muscles indicate that marsupial herbivores
exhibit different specializations for grazing and browsing.
No studies, however, have examined the skulls of
marsupial herbivores to determine the relationship
between stress and strain, and the evolution of skull
shape. The relationship between skull morphology, biomechanical
performance, and diet was tested by applying
the finite element method to the skulls of four
marsupial herbivores: the common wombat (Vombatus
ursinus), koala (Phascolarctos cinereus), swamp wallaby
(Wallabia bicolor), and red kangaroo (Macropus
rufus). It was hypothesized that grazers, requiring
stronger skulls to process tougher food, would have
higher biomechanical performance than browsers. This
was true when comparing the koala and wallaby
(browsers) to the wombat (a grazer). The cranial model
of the wombat resulted in low stress and high mechanical
efficiency in relation to a robust skull capable of
generating high bite forces. However, the kangaroo,
also a grazer, has evolved a very different strategy to
process tough food. The cranium is much more gracile
and has higher stress and lower mechanical efficiency,
but they adopt a different method of processing food by
having a curved tooth row to concentrate force in a
smaller area and molar progression to remove worn
teeth from the tooth row. Therefore, the position of the
bite is crucial for the structural performance of the
kangaroo skull, while it is not for the wombat which
process food along the entire tooth row. In accordance
with previous studies, the results from this study show
the mammalian skull is optimized to resist forces generated
during feeding. However, other factors, including
the lifestyle of the animal and its environment, also
affect selection for skull morphology to meet multiple
functional demands.
Click here to download the original DICOM dataset (216 Mb).
About the Species
This specimen, whose sex is unknown, was collected in Balranald, New South Wales, Australia on 23 August 1962. It was made available to DigiMorph.org by Dr. Alana Sharp of the University of New England.
About this Specimen
The skull and mandible were scanned separately at St. Vincent's Public Hospital in Melbourne, Australia, by Shelley O'Hara and Alana Sharp, using a Siemens Sensation 64 scanner. The skull was scanned along the coronal axis for a total of 706 slices, with an interslice spacing of 0.30 mm and an interpixel spacing of 0.21 mm.
Click here to download the original DICOM dataset (216 Mb).
About the Scan
Literature
Sharp, A. In press. Comparative finite element analysis of the cranial performance of four herbivorous marsupials. Journal of Morphology.
Links
Macropus rufus page on Wikipedia
M. rufus page on the Animal Diversity Web (University of Michigan Museum of Zoology)
Literature & Links
None available.
Additional Imagery
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