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

标题：合作研究：五大湖地区晚第四纪长鼻类灭绝的年代学和古生态学（美国）Chris Widga1、Stacey Lengyel1、Greg Hodgins2、Jeff Saunders1、J. Douglas Walker31。景观历史项目，伊利诺伊州立博物馆，斯普林菲尔德，伊利诺伊州2。亚利桑那大学 NSF AMS 设施，图森，AZ3。堪萨斯大学地质系，劳伦斯，堪萨斯州更新世末期 35 属北美哺乳动物灭绝的潜在因素引发了一个多世纪以来的激烈争论。问题在于，灭绝的主要驱动因素是否是人类狩猎或与气候相关的景观变化、其他拟议的灾难性过程对巨型动物种群的影响，还是上述因素的任何组合。不幸的是，区域长鼻动物灭绝时间的模糊性使得实际灭绝事件与文化和气候时间表的严格比较变得复杂。这项研究将通过对研究区域约 80 只猛犸象和乳齿象组合的直接测年，改进五大湖地区第四纪晚期长鼻类灭绝的年代学，该区域的灭绝现象似乎特别持久。该项目还将通过检查牙齿和骨骼中动物饮食（ä13C）、季节性（ä18O）和流动性（87Sr/86Sr）的同位素记录，以及个体生活史（例如生长速度、病理学）的骨骼记录，完善我们对长鼻类生态位区域进化的理解。这些数据集将用于定义过去~50ka期间长鼻动物生态位结构的变化，并随后根据这些长期模式检查更新世末期长鼻动物的生态位结构。这些平行的年代学和古生态学研究将用于阐明推测长鼻类动物灭绝前生态位变化的因素，并研究拟议的灭绝过程（例如人类狩猎、植被变化）在长鼻类动物从五大湖地区消失的过程中的相对重要性。年代久远的长鼻类遗骸，结合对个体生活史、饮食和流动模式的分析，将有助于深入了解五大湖地区更新世末期生态系统的结构，包括拟议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，这些阈值对于维持现代大型哺乳动物种群在快速变化的气候条件下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.