COMPARING COMMUNITY STRUCTURE AND HABITAT OF TWO MIDDLE MIOCENE NEOTROPICAL FOSSIL LOCALITIES USING ECOLOGICAL DIVERSITY ANALYSIS (EDA)

Ecological Diversity Analysis (EDA) is a technique that uses ecological attributes of mammals to reconstruct the community structure and habitat of a fossil locality. EDA was developed to study late Cenozoic, hominin-yielding sites in Africa and has subsequently been applied to older Cenozoic sites on other continents. EDAs of South American paleofaunas have generally relied on modern comparative datasets from that continent, but modern faunas from other continents may be more appropriate models considering the high-level taxonomic differences that exist between modern and fossil South American mammal communities. In order to test this hypothesis as well the influence of habitat on mammal provinciality in South America, we selected two well-sampled and roughly contemporaneous middle Miocene (13–12 Ma) localities, La Venta, Colombia (LV) and Quebrada Honda, Bolivia (QH), that share virtually no taxa and for which independent paleoenvironmental data have been published (e.g., paleosols, ichnofossils). We coded ca. 2,450 modern mammal species from 147 sites spanning six continents for three ecological attributes: diet (bark, fruit, grass, leaves, seeds, invertebrates, vertebrates, omnivore), locomotor habit (arboreal, scansorial, terrestrial, fossorial, semi-fossorial, semi-aquatic), and body mass (six exponential categories), calculated percentages of species in each attribute category, and compared them to the two paleofaunas using non-metric multi-dimensional scaling and hierarchical clustering. In both analyses, LV and QH were found to be most similar to modern Afrotropical and Australasian faunas, grouping with habitats similar to those inferred from previous paleoenvironmental studies (moist, heavily forested habitats for LV and drier, more open habitats for QH). Our study suggests that modern communities from other continents may be more appropriate analogues for ancient Neotropical communities than modern South American ones. It also provides additional support for regional habitat differentiation as an explanation for the development of significant mammalian faunal provinciality in South America during the Miocene.