COLLABORATIVE RESEARCH: On Middle Miocene Biogeography and Biostratigraphy in the Northern Rocky Mountains of Idaho, Montana, and Wyoming

本项目继续研究中中新世构造运动对落基山脉北部哺乳动物生物地理格局的影响。该项目将测试关于形态模式、生物地理模式和爱达荷州、蒙大拿州和怀俄明州中第三纪不整合发展之间一致性的假设。研究将重点解释5个山间盆地Barstovian矿床的地鼠、袋鼠鼠等类地鼠的地质年代学和生物地理格局。geomyooid啮齿动物是焦点，因为它们在不整合形成后经历了明显的辐射。计算机成像技术和地理信息系统技术，结合演化学方法，将用于分析每一个盆地中年代确定的地层中大量的geomyoid牙体遗骸的生物地理意义，以及从大平原和大盆地的其他地方获得的适当的比较材料。该研究在以下方面具有广泛的兴趣：(1)在很少受到关注的时间尺度（2-3百万年）上确定地质和生物过程之间的相互作用；(2)应用新的古生物学技术（成像和地理信息系统），使我们能够解决古生物学家（进化、物种形成）和地质学家（盆地形成年代学）都感兴趣的问题；(3)完善中新世中期磁地层学、脊椎动物生物年代学和辐射时间尺度之间的联系；这对了解北落基山脉的构造演化至关重要。

This project continues work on the effect of middle Miocene tectonism on mammalian biogeographic patterns in the northern Rocky Mountains. The project will test hypotheses concerning the concordance between morphologic patterns, biogeographic patterns and development of the Mid-Tertiary unconformity in Idaho, Montana, and Wyoming. The study will focus on interpreting the geochronologic and biogeographic patterns of the geomyoid rodents (gophers, kangaroo rats, and such) from Barstovian deposits in 5 intermontane basins. Geomyoid rodents are the focus because they underwent a pronounced radiation just after the unconformity developed. Computerized imaging and Geographic Information System techniques, combined with a cladistic approach, will be used to analyze the biogeographic meaning of the abundant geomyoid dental remains from well-dated horizons in each of the basins, as well as appropriate comparative material from other localities in the Great Plains and Great Basin. The research is of widespread interest in (1) identifying the interplay between geologic and biotic processes on a timescale that has received little attention (2-3 million years); (2) applying new paleontological techniques (imaging and GIS) that allow us to address problems of interest to both paleontologists (evolution, speciation) and geologists (chronology of basin formation) and (3) refining links of the magnetostratigraphic, vertebrate biochronologic, and radiometric time scales in the middle Miocene, which is critical for understanding the tectonic evolution of the northern Rockies.