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Stegosaur osteoderm distribution, center of mass, and humeral shape (free pdf)



From: Ben Creisler
bcreisler@gmail.com

A new paper in the now open-access journal Fossil Record (older issues
are not open access):


Heinrich Mallison (2014)
Osteoderm distribution has low impact on the centre of mass of stegosaurs.
Fossil Record 17: 33-39
doi:10.5194/fr-17-33-2014
http://www.foss-rec.net/17/33/2014/fr-17-33-2014.html

It has been hypothesized that the pronounced differences of stegosaur
humeral shapes, with large forms having more slender and small forms
having more robust humeri, may be explained by a difference in
relative centre of mass (COM) placement caused by differing
distributions of osteoderms. To test this hypothesis, digital 3-D
models of the bones and osteoderms of the Tanzanian stegosaur
Kentrosaurus aethiopicus and of the North American stegosaur
Stegosaurus armatus were used to create a 3-D computer-aided design
life reconstruction. On these models osteoderm placement was varied
drastically, recreating both existing and hypothetical forms. These
models show that COM position varies somewhat with realistic osteoderm
distributions, but insufficiently to explain major differences in
humeral shape. The uniform weight distribution between forelimbs and
hindlimbs found between the two taxa also casts doubt on the
hypothesis that differences in relative COM position caused by other
factors than osteoderm distribution can explain differences in humeral
robustness.