Mammals and mollusks across the Cretaceous-Tertiary boundary from Makoshika State Park and vicinity (Williston Basin), Montana
Mammals and mollusks across the Cretaceous-Tertiary boundary from Makoshika State Park and vicinity (Williston Basin), Montana
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蒙大拿州马科希卡州立公园及附近地区（威利斯顿盆地）跨越白垩纪-第三纪边界的哺乳动物和软体动物
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发表时间：
1997
期刊：
影响因子：
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通讯作者：
D. Krause
中科院分区：
文献类型：
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作者：
J. Hunter;J. Hartman;D. Krause
在蒙大拿州格伦迪夫附近的Makoshika州立公园及周边地区的荒地中，大量露头暴露出一系列连续的含矿河流三角洲沉积岩，横跨白垩纪-第三纪（K/T）边界两侧。这种偶然的情况下，使我们能够记录在这段时间内的哺乳动物区系组成的变化，与观察到的模式组成的polynomorph和软体动物的变化，并测试假设的动物区系营业额在K/T边界。特别令人感兴趣的是古代有蹄类哺乳动物的外观和多样化，因为同时恐龙灭绝沿着有蹄类动物的辐射已被调用在模型中的动物群逐渐变化的K/T边界。在Makoshika国家公园及其附近的六个地方发现了化石哺乳动物。已知的样本代表三个连续的当地动物群。来自地狱溪组（上白垩纪）的泥头鲸当地动物群的组成类似于蒙大拿州和怀俄明州其他地方的兰溪北美陆地哺乳动物“时代”（NALMA）。从联合堡组（古新世）卢德洛段下部发现的希亚特当地动物群的组成与北方纬度的普尔坎NALM动物群相似。希亚特当地动物群中存在的古代有蹄类动物的多样组合与负面证据（没有多瘤Taeniolabis taoensis，其出现标志着晚期普尔坎的到来）表明，希亚特当地动物群不年轻于中期普尔坎（Pu 2）。学校井当地动物群（暂定名为Torrejonian NALMA）出现在联合堡地层的卢德洛段。产出典型晚白垩世哺乳动物的地层与产出古新世早期哺乳动物的地层相隔约20 m。Makoshika国家公园的K/T边界已经在孢粉的基础上得到了更详细的确认。花粉研究导致了对蕨类植物穗的初步鉴定，其他人在K/T边界上方的其他地方注意到了这一点。缺乏任何类型的虫溪脊椎动物组合表明，有争议的“Bugcreekian”生物时（Pu 0）不能外推到这个地区。远古有蹄类动物的进化辐射可能直到恐龙灭绝之后才开始。
Extensive outcrops in the badlands of Makoshika State Park near Glendive, Montana, and surrounding areas expose a continuous sequence of fossiliferous, fluviodeltaic sedimentary rock spanning both sides of the Cretaceous-Tertiary (K/T) boundary. This fortuitous circumstance has enabled us to document change in the composition of mammalian faunas during this time, to relate observed patterns to palynomorph and molluscan changes in composition, and to test hypotheses of faunal turnover at the K/T boundary. Of particular interest is the appearance and diversification of archaic ungulate mammals, since simultaneous dinosaur extinction along with ungulate radiation has been invoked in models of gradual faunal change at the K/T boundary. Fossil mammals have been recovered from six localities in and near Makoshika State Park. The known samples represent three successive local faunas. Composition of the Muddy Tork Local Fauna from the Hell Creek Formation (Upper Cretaceous) resembles those of the Lancian North American Land Mammal "Age" (NALMA) from elsewhere in Montana and Wyoming. Composition of the Hiatt Local Fauna recovered from lower parts of the Ludlow Member of the Fort Union Formation (Paleocene) resembles faunas of the Puercan NALMA at northern latitudes. The diverse assemblage of archaic ungulates present in the Hiatt Local Fauna in conjunction with negative evidence (absence of the multituberculate Taeniolabis taoensis, the appearance of which marks the advent of the late Puercan) suggests that the Hiatt Local Fauna is no younger than middle Puercan (Pu2). The School Well Local Fauna (tentatively, Torrejonian NALMA) occurs higher in the Ludlow Member of the Fort Union Formation. Strata yielding typical Late Cretaceous mammals are separated stratigraphically from those yielding early Paleocene mammals by about 20 m. The K/T boundary in Makoshika State Park has been recognized in more detail on the basis of palynomorphs. Pollen studies have led to preliminary identification of a fern spike, noted elsewhere by others immediately above the K/T boundary. Lack of any type of Bug Creek vertebrate assemblage suggests that the controversial "Bugcreekian" biochron (Pu0) cannot be extrapolated to this area. Evolutionary radiation of archaic ungulates may not have begun until after dinosaur extinction.