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



It's interesting that for certain Late Cretaceous ecosystems (e.g.,
Laramidia), it would have been herbivorous theropods that were best
equipped to feed on the highest branches, not ornithischians.  In the
absence of sauropods, the hadrosaurs had the greatest potential
maximum feeding height (~ 5 m) - but only when bipedal.  Adult
hadrosaurs were more comfortable as quadrupeds (e.g., Dilkes, 2001;
Maidment & Barrett, 2012), as noted by Mallon et al.


In contrast, theropods such as ornithomimids and therizinosaurids were
habitually bipedal.  The modestly-sized _Struthiomimus_, with a head
height of around 3m, could have nibbled branches higher than a
quadrupedal hadrosaur could.  The forelimbs of ornithomimids and other
putatively herbivorous theropods (oviraptorosaurs, therizinosaurs)
could have been used to bring even higher branches within reach of the
mouth.





Cheers

Tim




On Sat, Jun 15, 2013 at 12:22 PM, Ben Creisler <bcreisler@gmail.com> wrote:
> 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.