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Jaw mechanics and evolutionary paleoecology of Alberta megaherbivorous dinosaurs

Ben Creisler

A new online paper:

Jordan C. Mallon & Jason S. Anderson (2015)
Jaw mechanics and evolutionary paleoecology of the megaherbivorous
dinosaurs from the Dinosaur Park Formation (upper Campanian) of
Alberta, Canada.
Journal of Vertebrate Paleontology (advance online publication)

The question of what role differential jaw mechanics may have played
in facilitating dietary niche partitioning among Late Cretaceous
megaherbivorous dinosaurs from Laramidia is examined, using the fossil
assemblage of the Dinosaur Park Formation as a test case. We use
phylogenetic inference to reconstruct the mandibular adductor
musculature of these animals, which we then apply to the construction
of biomechanical lever models of the mandible to estimate relative
bite forces. Our findings reveal predictably weak bite forces in
ankylosaurs, and comparatively high bite forces in ceratopsids and
hadrosaurids, both of which possessed a mechanical advantage that
produced bite forces 2–3 times higher than those forces exerted by the
adductor musculature. The impressive jaw mechanism shared by the last
two taxa evolved in a stepwise fashion, independently in each lineage.
There is tentative evidence to suggest that nodosaurids had more
powerful bites than ankylosaurids, but the overall mechanical
diversity among megaherbivores from the Dinosaur Park Formation is
low, suggesting that differential jaw mechanics could have played only
a subsidiary role in niche partitioning. Such mechanical conservatism
may have may have been selected for, or it may simply reflect the
limits imposed by evolutionary constraints. Regardless, mechanical
disparity patterns remained stable throughout the ~1.5 Ma evolution of
the Dinosaur Park Formation megaherbivore chronofauna.