Ecological Diversity of Miocene Mammals of Pakistan

Regents Of The University Of Michigan - Ann Arbor, Ann Arbor MI

Investigators

Abstract

Ecological diversity of Miocene mammals of Pakistan Catherine Badgley, Thure Cerling, Anna K. Behrensmeyer, John C. Barry EAR-0125663 Abstract This collaborative project evaluates the ecological and evolutionary responses of mammals to changes in climate and vegetation during the late Miocene (5 to 11 million years ago), as known from the terrestrial record of Pakistan. Fossils and sedimentary rocks of northern Pakistan are well documented by the work of our international research team that has conducted over 25 years of field work on the geology, paleontology, and paleoecology of the Siwalik sequence. (Siwalik refers to fluvial sediments shed by the rising Himalayas over the last 20 million years.) Work to date on Siwalik sediments and vertebrate fossils, especially mammals, has provided a detailed record of changing fluvial systems, climate and vegetation, preservational attributes of fossil assemblages, and mammalian faunas. This record is one of the best documented continental ecosystems of the Cenozoic and now presents the opportunity to evaluate changes in taxonomic composition, speciation, immigration, local extinction, and ecological attributes of mammalian species and faunas in relation to sustained environmental change. Our project involves first the creation of an electronic database (the Siwalik species database) for fossil mammals. The database will contain ecologically informative, specimen-based measurements, including morphological and isotopic data for each species. Next, we will use this compilation of data to test three models of how mammalian faunas changed over time. One model focuses on the direct effects of changing climate and vegetation on the composition and ecological attributes of mammals. The second model evaluates whether or not species with large geographic ranges and high local abundance dominate the pattern of faunal change. The third model examines the hypothesis that the arrival of several species of extremely large mammals (the size of elephants) altered the local habitat through feeding and trampling and caused changes in the rest of the ecological community. Each model makes a unique set of predictions about the timing and nature of faunal change in relation to environmental change. These predictions will be tested with the data assembled in the database. The Siwalik species database will stabilize the taxonomic and ecological data for Siwalik mammals and make these data accessible for other studies of Old World history. Tests of the three models of faunal change will demonstrate how the fossil record contributes to patterns and theory in community ecology.