Document Type

Thesis

Abstract

The terrestrial Early Cretaceous (121-98.9 Ma) of western North America is represented by several formations that record a wide temporal and geographic range of environments and document major faunal changes between the Late Jurassic and the Late Cretaceous; however, relatively little is known about the paleoecology of these Early Cretaceous terrestrial communities. Vertebrate microfossil assemblages offer a promising means of quantifying paleoecology by offering large, diverse samples of parautochthonous taxa. In this study, four newly discovered microvertebrate sites from the Cloverly Formation are used to assess the composition and structure of the assemblage. By identifying specimens to the lowest possible taxonomic level, and documenting general anatomical and phylogenetic data for each taxon, qualitative paleoecology could be inferred for each site. Rarefaction helped control for sampling bias, and the four Cloverly microsites were compared with sites in penecontemporaneous formations as a means of observing taxon geographic distributions and potential Early Cretaceous ecological patterns. Principle coordinates analysis was applied to the taxon presence-absence data from the nine Early Cretaceous microsites, and non-metric multidimensional scaling was used to quantify differences in taxon abundance. Specimen identifications from our sample of Cloverly microvertebrates greatly increased the known taxonomic diversity of the Cloverly Formation, especially with respect to aquatic forms. Preliminary paleoenvironmental and paleoecological reconstructions revealed both predominantly terrestrial and predominantly aquatic sites within the formation, although several aquatic and terrestrial taxa were ubiquitous.

Date Awarded

2007

Department

Geology

Advisor 1

Rowan Lockwood

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