The Vertebrate Paleontology of Cement Creek Cave, Colorado

steven D. Emslie, David Meltzer， and David WebsterNSF Proposal # 0819668在这项研究中，我们将完成在美国科罗拉多州上甘尼森盆地一个重要的晚更新世地区水泥溪洞（CEMENT CREEK CAVE）中发现的脊椎动物化石的详细系统鉴定和分析（放射性碳、稳定同位素）。1998年对该遗址进行的初步工作揭示了极其丰富的古生物记录，其中有大量的脊椎动物和植物遗骸，可以追溯到45,000多年前的最后一个冰河时代，直到最近的2000年。从这个洞穴中发现的化石意义重大：在北美其他高海拔地区，没有任何一个地方能发现几乎连续的脊椎动物化石，可以追溯到上一个冰河期前后（冰河期的高峰大约在2万到1.8万年前）。对1998年发掘中发现的鼩鼱化石（Sorex spp.）和其他分类群的分析表明，洞穴周围的环境随着时间的推移发生了重大变化，从苔原到亚高山森林再到混合的山艾草草原环境。然而，放射性碳分析也显示，洞穴化石序列中有很大的空白，这似乎与冰川历史的片段有关。这些差距是否真实尚不确定；水泥溪记录可以追溯到多远，以及是否可以从这个丰富的化石地点得出更精确的生态和气候序列，这些问题也同样令人担忧。因此，在2007年夏天，我们重新开放了1998年挖掘的区域，并将1998年的原始测试坑扩大到1 x 1.5米，并在5厘米的水平上挖掘到2.2米的深度。这些更广泛的挖掘使洞穴中地层剖面的深度增加了一倍，并为收藏增添了数千种脊椎动物化石。这一扩展也为本文提出的进一步分析提供了更丰富的化石材料组合，以探索和测试关于更新世晚期和全新世的气候变化和小型哺乳动物群落结构和饮食的假设。在这里，从这次新挖掘中发现的化石将被分类并完成详细的鉴定。对1998年发掘的剩余不明材料的分析也将完成，以提供自威斯康星时期以来上甘尼森盆地脊椎动物群落和环境变化的更彻底的重建。这项研究将在北卡罗来纳大学威尔明顿分校的三名本科生和南卫理公会大学的一名研究生的协助下进行。这些学生将参与实地和实验室研究，并将使用科学方法和假设检验对洞穴化石进行独立研究。学生将受益于先进的研究经验和培训，将参加博物馆参观化石标本的详细分析，并将发展他们的科学调查和写作技能。来自新大的配套资金将用于该机构的研究生参与这项研究，以及如何将其应用于上甘尼森盆地的古印第安记录。公众演讲、网站和该项目的数据展览将促进公众对保护考古和古生物资源的价值和重要性的认识。这些报告也将强调洞穴资源的价值。

THE VERTEBRATE PALEONTOLOGY OF CEMENT CREEK CAVE, COLORADOSteven D. Emslie, David Meltzer, and David WebsterNSF Proposal #0819678In this study, we will complete detailed systematic identification and analysis (radiocarbon, stable isotope) of vertebrate fossils recovered from Cement Creek Cave, an important late Pleistocene locality in the Upper Gunnison Basin, Colorado. Preliminary work at this site in 1998 revealed an extremely rich paleontological record with abundant vertebrate and plant remains dating from before the last Ice Age, over 45,000 years ago, to more recent periods within the past 2000 years. The fossils from this cave are quite significant: no other high-elevation site in North America has produced a near-continuous record of fossil vertebrates that date before and after the last Ice Age (that peaked at about 20,000-18,000 years ago). Analysis of fossil shrews (Sorex spp.) and other taxa recovered in the 1998 excavations, including some species no longer found in Colorado or the Upper Gunnison Basin, indicate there were significant changes in the environment surrounding the cave over time ranging from tundra to subalpine forest to mixed sagebrush steppe environments. However, radiocarbon analyses also reveal there are large gaps in the cave fossil sequence, which seemingly correlate with episodes in glacial history. Whether those gaps are real is uncertain; so too are the questions of how far back the Cement Creek record might extend, and whether a more precise ecological and climatic sequence can be derived from this rich fossil locality. Consequently, in summer 2007 we reopened the area excavated in 1998 and expanded the original 1998 test pit to 1 x 1.5 m and excavated to a depth of 2.2 m in 5-cm levels. These more extensive excavations doubled the depth of the stratigraphic profile in the cave and added thousands more vertebrate fossils to the collections. This expansion also provided a richer assemblage of fossil material for additional analyses proposed here to explore and test hypotheses on climate change and small-mammal community structure and diet in the later Pleistocene and Holocene. Here, the fossils recovered from this new excavation will be sorted and detailed identification will be completed. Analysis of remaining unidentified material from the 1998 excavation also will be completed to provide a more thorough reconstruction of vertebrate communities and environmental change in the Upper Gunnison Basin since the Wisconsin Period. This research will be conducted with the assistance of three undergraduate students at the University of North Carolina, Wilmington, and one graduate student at Southern Methodist University. These students will be involved in field and laboratory research and will develop independent studies of the cave fossils using the scientific method and hypothesis testing. The students will benefit from advanced research experiences and training, will participate in museum visits for detailed analyses of fossil specimens, and will develop their skills at scientific investigation and writing. Matching funds from SMU will be used to involve the graduate student from that institution in this research and how it applies to the paleoindian record in the Upper Gunnison Basin. Public presentations, a web site, and exhibits of data from this project will advance public understanding on the value and importance of protecting archaeological and paleontological resources. The value of cave resources also will be stressed in these presentations.