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Dinosaur megaherbivore tooth morphology and wear in Dinosaur Park Formation, Alberta

Ben Creisler

New in PLoS ONE:

Jordan C. Mallon & Jason S. Anderson (2014)
The Functional and Palaeoecological Implications of Tooth Morphology
and Wear for the Megaherbivorous Dinosaurs from the Dinosaur Park
Formation (Upper Campanian) of Alberta, Canada.
PLoS ONE 9(6): e98605.

Megaherbivorous dinosaurs were exceptionally diverse on the Late
Cretaceous island continent of Laramidia, and a growing body of
evidence suggests that this diversity was facilitated by dietary niche
partitioning. We test this hypothesis using the fossil megaherbivore
assemblage from the Dinosaur Park Formation (upper Campanian) of
Alberta as a model. Comparative tooth morphology and wear, including
the first use of quantitative dental microwear analysis in the context
of Cretaceous palaeosynecology, are used to infer the mechanical
properties of the foods these dinosaurs consumed. The phylliform teeth
of ankylosaurs were poorly adapted for habitually processing
high-fibre plant matter. Nevertheless, ankylosaur diets were likely
more varied than traditionally assumed: the relatively large, bladed
teeth of nodosaurids would have been better adapted to processing a
tougher, more fibrous diet than the smaller, cusp-like teeth of
ankylosaurids. Ankylosaur microwear is characterized by a
preponderance of pits and scratches, akin to modern mixed feeders, but
offers no support for interspecific dietary differences. The shearing
tooth batteries of ceratopsids are much better adapted to high-fibre
herbivory, attested by their scratch-dominated microwear signature.
There is tentative microwear evidence to suggest differences in the
feeding habits of centrosaurines and chasmosaurines, but statistical
support is not significant. The tooth batteries of hadrosaurids were
capable of both shearing and crushing functions, suggestive of a broad
dietary range. Their microwear signal overlaps broadly with that of
ankylosaurs, and suggests possible dietary differences between
hadrosaurines and lambeosaurines. Tooth wear evidence further
indicates that all forms considered here exhibited some degree of
masticatory propaliny. Our findings reveal that tooth morphology and
wear exhibit different, but complimentary, dietary signals that
combine to support the hypothesis of dietary niche partitioning. The
inferred mechanical and dietary patterns appear constant over the 1.5
Myr timespan of the Dinosaur Park Formation megaherbivore chronofauna,
despite continual species turnover.