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Herbivorous dinosaur feeding height in Dinosaur Park Formation of Alberta (free pdf)



From: Ben Creisler
bcreisler@gmail.com

This recent paper (from two months ago!) somehow did not get mentioned
on the DML. My bad, I guess. Anyway, it's open access:

Jordan C. Mallon, David C. Evans, Michael J. Ryan & Jason S. Anderson (2013)
Feeding height stratification among the herbivorous dinosaurs from the
Dinosaur Park Formation (upper Campanian) of Alberta, Canada.
BMC Ecology 13:14
DOI: 10.1186/1472-6785-13-14
http://link.springer.com/article/10.1186/1472-6785-13-14

Background

Herbivore coexistence on the Late Cretaceous island continent of
Laramidia has been a topic of great interest, stemming from the
paradoxically high diversity and biomass of these animals in relation
to the relatively small landmass available to them. Various hypotheses
have been advanced to account for these facts, of which niche
partitioning is among the most frequently invoked. However, despite
its wide acceptance, this hypothesis has not been rigorously tested.
This study uses the fossil assemblage from the Dinosaur Park Formation
of Alberta as a model to investigate whether niche partitioning
facilitated herbivorous dinosaur coexistence on Laramidia.
Specifically, the question of feeding height stratification is
examined in light of the role it plays in facilitating modern ungulate
coexistence.

Results

Most herbivorous dinosaur species from the Dinosaur Park Formation
were restricted to feeding no higher than approximately 1 m above the
ground. There is minimal evidence for feeding height partitioning at
this level, with ceratopsids capable of feeding slightly higher than
ankylosaurs, but the ecological significance of this is ambiguous.
Hadrosaurids were uniquely capable of feeding up to 2 m quadrupedally,
or up to 5 m bipedally. There is no evidence for either feeding height
stratification within any of these clades, or for change in these
ecological relationships through the approximately 1.5 Ma record of
the Dinosaur Park Formation.

Conclusions

Although we cannot reject the possibility, we find no good evidence
that feeding height stratification, as revealed by reconstructed
maximum feeding heights, played an important role in facilitating
niche partitioning among the herbivorous dinosaurs of Laramidia. Most
browsing pressure was concentrated in the herb layer, although
hadrosaurids were capable of reaching shrubs and low-growing trees
that were out of reach from ceratopsids, ankylosaurs, and other small
herbivores, effectively dividing the herbivores in terms of relative
abundance. Sympatric hadrosaurids may have avoided competing with one
another by feeding differentially using bipedal and quadrupedal
postures. These ecological relationships evidently proved to be
evolutionarily stable because they characterize the herbivore
assemblage of the Dinosaur Park Formation through time. If niche
partitioning served to facilitate the rich diversity of these animals,
it may have been achieved by other means in addition to feeding height
stratification. Consideration of other feeding height proxies,
including dental microwear and skull morphology, may help to alleviate
problems of underdetermination identified here.