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Vertebrate paleontology of the Cloverly Formation--Paleoecology

Ben Creisler

A new paper:

Matthew T. Carrano, Matthew P. J. Oreska & Rowan Lockwood (2016)
Vertebrate paleontology of the Cloverly Formation (Lower Cretaceous),
II: Paleoecology.
Journal of Vertebrate Paleontology (advance online publication)

Vertebrate microfossil assemblages in terrestrial formations are a
promising source of data on the structure of fossil metacommunities.
However, the degree to which these deposits capture true,
metacommunity-level samples is unknown. Individual deposits may be
biased in ways that limit their utility for intra- and inter-formation
comparisons. This study describes the composition of ten vertebrate
microfossil assemblages collected from the Lower Cretaceous Cloverly
Formation in Montana and Wyoming, U.S.A., and evaluates whether the
assemblages are sufficiently similar to suggest the presence of a
single Cloverly metacommunity, or ‘paleocommunity type.’ The
assemblages appear to be biased by factors related to the preferential
incorporation and preservation of different taxa and skeletal element
types, which compound with decreasing locality sample size. Less
productive localities lack whole taxonomic groups, especially small,
fully terrestrial vertebrates. Only the two vertebrate microfossil
bonebeds approach the known formation richness. High individual tooth
counts overrepresent particular species, especially the crocodylians.
Despite these biases, the multiple assemblages nevertheless yield
statistically similar taxon abundance rank orders, suggesting the
presence of a single, formation-wide paleo-metacommunity, which bears
resemblance to a viable metacommunity. The aggregate assemblage
exhibits an ‘Eltonian pyramid’ trophic hierarchy for both terrestrial
and aquatic taxa. Comparing the multiple assemblages synoptically also
reveals possible landscape-scale abundance patterns for particular
species. Taken together, microvertebrate assemblages offer insight
into regional paleo-metacommunities and provide samples for
inter-formational comparisons at this level.