Collaborative Research: Chronology and Ecology of Late Pleistocene Megafauna at Rancho La Brea

在加州的洛杉矶的拉布雷亚牧场沥青坑里，有数千块大型哺乳动物的骨头--可怕的狼、剑齿猫、郊狼、灭绝的野牛、马和其他动物--这些骨头在上一个冰河时代被困在粘性的表面石油沉积物中。这一无与伦比的化石组合使人们能够对灭绝的哺乳动物生物学进行严格的研究，特别是在大多数化石地点都很罕见的食肉动物。拉布雷亚化石跨越了地球历史上的一个关键时期（大约5万年前到现在），其中包括最后一个冰河时代的结束，人类在北美的到来，以及导致大陆上三分之二大型哺乳动物死亡的灭绝等重大事件。这种独特的存款将被用来调查之间的关系，主要的环境变化和进化的变化（大小，饮食等）。在大型哺乳动物中，这些信息对促进当今野生动物的生存至关重要。该项目涉及通过焦油坑博物馆在大洛杉矶地区进行重大的社区推广，并将创建教育内容，供全国各地的高中教师在线使用。在兰乔拉布雷亚进行系统级研究的主要障碍是缺乏放射性碳年代测定，以及由此导致的无法将生物变化与时间联系起来。该项目将对过去5万年多个坑中的样品进行密集的放射性碳年代测定，以建立四种灭绝的大型哺乳动物物种和一种现存物种的第一个详细的年代学。这将涉及收集和汇编这些物种的普查数据，以跟踪总丰度和多样性的变化，以及形态和饮食变化的数据。一个清晰的年表将使这些关于哺乳动物进化变化和更新世巨型动物群的数据与现有的主要古环境变化记录联系起来。这项工作将对我们理解哺乳动物生态学的保护、生存、环境变量和人类产生广泛的影响，这与现代保护直接相关。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的知识价值和更广泛的影响审查标准进行评估来支持。

The Rancho La Brea tar pits of Los Angeles, California contain thousands of bones from large mammals --dire wolves, sabertooth cats, coyotes, extinct bison, horses, and others-- trapped in sticky surface oil deposits during the last Ice Age. This unparalleled fossil assemblage allows rigorous studies of extinct mammal biology, especially of carnivores which are rare at most fossil sites. The La Brea fossils span a critical time in Earth's history (approximately 50,000 years ago to the present) that includes major events such as the end of the last Ice Age, the arrival of humans in North America, and an extinction that killed two thirds of the large mammals on the continent. This unique deposit will be used to investigate relationships between major environmental changes and evolutionary variation (size, diet, etc.) in large mammals, information that is critical for promoting the survival of wildlife today. The project involves significant community outreach in the greater Los Angeles area through the Tar Pits Museum and will create educational content that will be available online for high school teachers across the country. The major impediment to system-level study at Rancho La Brea is a paucity of radiocarbon dates and the resulting inability to correlate biotic change with time. This project will intensively radiocarbon date samples from multiple pits spanning the last 50,000 years to establish the first detailed chronology for the entrapment of four extinct species of large mammals, and one extant species. It will involve the collection and compilation of census data for these species to track changes in total abundance and diversity, as well as data on morphological and dietary changes. A well-resolved chronology will allow these data on evolutionary changes in mammals and the Pleistocene megafaunal extinctions to be linked to existing records of major paleo-environmental changes. This work will have broad implications for our understanding of extinctions, survival, environmental variables, and humans on mammalian ecology, which is directly relevant to modern conservation.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.