Late Cretaceous ("Edmontonian") Vertebrate Faunas and Geology of the Williams Fork Formation, N.W. Colorado

对西部内陆晚白垩世脊椎动物动物群的了解少于第三纪脊椎动物。对于鲜为人知的“埃德蒙顿”时代的哺乳动物动物群来说，情况尤其如此。来自科罗拉多州西北部威廉姆斯福克地层的一种新的动物群，是这个时代第一个确定的产哺乳动物的动物群。这些哺乳动物将作为审查跨越鲜为人知的“埃德蒙顿学派”的物种的基础，也将作为材料所保证的更高级别关系分析的基础。基于氨性和花粉的分带非常有力地证明，脊椎动物在年龄上最好被视为“埃德蒙顿人”。四个菊石带，Didymoceras cheyennense到Baculites reeside i，包围着脊椎动物群，到目前为止，它们来自Williams Fork FM的下半部分。在接下来的三年里，使用屏幕清洗技术和重液分离技术收集的大型微脊椎动物样本将更全面地记录这一鲜为人知的动物群间隔。对沉积学和地层学(很快还有孢粉学和磁性地层学)的分析将有助于建立生物地层学框架。

Knowledge of Late Cretaceous vertebrate faunas in the Western Interior is less than for Tertiary vertebrates. This is particularly true for mammalian faunas of the very poorly known "Edmontonian" age. A new fauna from the Williams Fork Formation, NW Colorado, is the first definitive mammal-producing fauna of this age. The mammals will serve as a basis for a review of species that span the poorly known "Edmontonian" and will also serve as a basis for analyses of higher-level relationships as warranted by the material. Zonations based upon ammonities and pollen argue very strongly that the vertebrates are best regarded as "Edmontonian" in age. Four ammonite zones, Didymoceras cheyennense through Baculites reesidei, bracket the vertebrate faunas, which so far are from the lower half of the Williams Fork Fm. Large microvertebrate samples to be collected over the next three years using screenwashing techniques and heavy liquid separation will more fully document this poorly know faunal interval. Analysis of both sedimentology and stratigraphy (and soon palynology and hopefully magnetostratigraphy) will be helpful in establishing a biostratigraphic framework.