Collaborative Research: Chronology and Paleoecology of late Quaternary Proboscidean Extinctions in the Great Lakes Region (USA)

标题：合作研究：大湖区晚第四纪ProBoscides灭绝的年代学和古生态学(美国)Chris Widga 1，Stacey Lengyel1，Greg Hodgins2，Jeff Saunders1，J.Douglas Walker31。伊利诺伊州博物馆风景历史项目，伊利诺伊州斯普林菲尔德，IL2。亚利桑那大学-NSF AMS设施，图森，AZ3。堪萨斯大学地质系，劳伦斯，康涅狄格州康涅狄格州更新世晚期，北美35种哺乳动物灭绝的原因引发了一个多世纪的激烈辩论。有争议的问题是，物种灭绝的主要驱动力是人类狩猎还是与气候有关的景观变化，其他拟议的灾难性过程对大型动物种群的影响，还是上述因素的任何组合。不幸的是，地区性脊椎动物灭绝的时间不明确，使得实际灭绝事件与文化和气候时间线的严格比较变得复杂起来。这项研究将通过直接测定来自研究区的约80个猛犸象和乳齿象组合的年代学，来改进大湖区长吻目动物灭绝的晚第四纪年代学，而在这个地区，这些灭绝似乎特别持久。该项目还将通过研究牙齿和骨骼中动物食性(ä13C)、季节性(ä18O)和流动性(87Sr/86Sr)的同位素记录，以及个体生活史的骨骼记录(例如，生长速度、病理)，来加深我们对长吻类生态位区域演化的理解。这些数据集将被用来确定近50ka来鼻目动物生态位结构的变化，并随后根据这些长期模式来研究更新世末期长吻目动物的生态位结构。这些平行的年代学和古生态研究将被用来阐明在大湖灭绝之前喙类生态位可能发生变化的因素，并研究拟议的灭绝过程(例如，人类狩猎、植被变化)在大湖地区喙类消失中的相对重要性。当结合对个体生活史、饮食和活动模式的分析时，过时的长吻类遗骸将提供对大湖区更新世末期生态系统结构的洞察，包括所提出的灭绝驱动因素的相对重要性。该项目还有可能确定生态阈值，这些阈值对于在快速变化的气候条件下保持现代大型哺乳动物种群的生存能力非常重要。

Title: Collaborative Research: Chronology and Paleoecology of late Quaternary Proboscidean Extinctions in the Great Lakes Region (USA)Chris Widga1, Stacey Lengyel1, Greg Hodgins2, Jeff Saunders1, J. Douglas Walker31. Landscape History Program, Illinois State Museum, Springfield, IL2. University of Arizona-NSF AMS Facility, Tucson, AZ3. Department of Geology, University of Kansas, Lawrence, KSThe factors underlying the extinction of 35 genera of North American mammals during the terminal Pleistocene have incited lively debate for over a century. At issue is whether the primary driver of extinctions was human hunting or climate-related landscape changes, the impact of other proposed catastrophic processes on megafaunal populations, or any combination of the above. Unfortunately, ambiguity in the timing of regional proboscidean extinctions has complicated rigorous comparisons of actual extinction events to cultural and climatic timelines. This study will improve the late Quaternary chronology of proboscidean extinctions in the Great Lakes region through direct dating of ~80 mammoth and mastodont assemblages from the study area, a region where these extinctions appear particularly protracted. The project will also refine our understanding of regional evolution in proboscidean ecological niches by examining isotopic records of animal diet (ä13C), seasonality (ä18O), and mobility (87Sr/86Sr) in teeth and bones, as well as skeletal records of individual life histories (e.g., growth rate, pathology). These datasets will be used to define changes in the niche structure of Proboscidea during the last ~50 ka, and to subsequently examine the niche structure of terminal Pleistocene proboscideans in light of these long-term patterns. These parallel chronological and paleoecological studies will be used to elucidate factors underlying presumed changes in proboscidean ecological niches immediately prior to extinction, and to examine the relative importance of proposed extinction processes (e.g., human hunting, vegetation changes) in the disappearance of proboscideans from the Great Lakes region. Dated proboscidean remains, when combined with analyses of individual life histories, diet, and mobility patterns, will offer insight into the structure of terminal Pleistocene ecosystems of the Great Lakes region, including the relative importance of proposed extinction drivers. This project also has the potential to identify ecological thresholds that are important to maintaining the viability of modern large mammal populations when exposed to rapidly changing climate conditions.