Standard palynological techniques (Traverse, 2007) will be used to reconstruct the assembly and evolution of plant communities across the Amazon region and through time and to evaluate trends in diversity, defined here as the number of different palynomorphs. Pollen, spores, and non-pollen palynomorphs will be identified utilizing modern atlases, databases, and reference collections, coupled with multiple descriptive studies of Cretaceous, Paleogene, and Neogene palynomorphs of South America. Palynomorph analyses will be complemented by analysis of organic biomarkers that can distinguish gymnosperms from angiosperms, quantify plant functional type (C3, C4, CAM), and provide other indicators of plant source composition (Diefendorf et al., 2012, 2014, 2015).

Palynomorphs have been used previously in many studies across multiple biomes to study plant diversity over a range of temporal scales (Harrington, 2004; Jaramillo et al., 2006), and although various transport and preservation processes can affect palynomorph representation, there is no reason to expect a systematic bias in taxonomic representation across varied sites or through time. We will interpret changes in diversity within the context of environmental inferences based on other tools (sedimentology, geochemistry, microfossils), use several different diversity metrics to evaluate palynomorph diversity trends, and apply various statistical tools to account for potential biases among sites and samples, such as differences in facies, sample size, or sample density.

The net result will be the first reconstructions of plant (palynomorph) diversity for the Amazon region spanning the entire Cenozoic and based on a consistent taxonomic and methodological approach.