TROPICAL ECOSYSTEM RESPONSE TO LATE-QUATERNARY ENVIRONMENTAL CHANGE: INSIGHT FROM REMARKABLE ASPHALT-PRESERVED BIOTAS

在大约12,000年前的最后一个冰河时代结束时，地球上大多数大型动物灭绝，许多生态系统发生了巨大变化。 科学家们仍然不知道为什么会发生这些变化，因为化石记录是不完整的，只保留了时间上的短暂快照。 一个例外是“沥青坑”，这是一个古生物学遗址，沥青（一种原油）在数千年的时间里渗透到地表，保存着整个生态系统的化石遗迹，包括骨骼、木材和昆虫。 在这个项目中，来自洛杉矶和秘鲁的科学家和大学生将共同努力，从秘鲁的一个沥青坑中挖掘和研究化石，重建生物多样性的冰河时代生态系统，并调查它是如何变成今天的贫瘠沙漠的。 这种生态系统崩溃发生在气候变化和人类影响的时期，类似于现在发生的情况。 人们希望研究这些过去的变化有助于防止未来的衰退。该项目将使北美和南美的学生和科学家参与恢复、识别和描述秘鲁北部沿海沥青地区（俗称“焦油坑”）的化石材料。 策划的植物群和动物群，包括植物，小型脊椎动物和无脊椎动物遗骸，将在这个研究不足的地区形成一个全面的和有科学价值的晚第四纪化石收藏，并将进行分析，以调查人类，气候和生物群落之间的相互作用。 本研究将围绕三个主要问题展开：（1）在更新世大型哺乳动物群落消失之前，西新热带沿海地区晚第四纪生态系统结构是什么？(2)该生态系统是如何、何时以及在何种气候和人为过程的作用下经历了巨大的生态状态变化，使其变成目前的荒漠化状况的？以及，（3）这些过程是如何与其他南美地区的环境变化和人为影响相结合，导致大陆和全球灭绝事件的？该奖项反映了NSF的法定使命，并被认为是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的支持。

At the end of the last Ice Age, about 12,000 years ago, most of the big animals on Earth went extinct and many ecosystems changed drastically. Scientists still don’t know why these changes happened because the fossil record is incomplete, preserving just brief snapshots in time. An exception are “tar pits,” paleontological sites where asphalt (a type of crude oil) seeped to the surface over thousands of years, preserving fossil remains of whole ecosystems including bones, wood, and insects. In this project, scientists and college students from Los Angeles and Peru will work together to excavate and study fossils from a Peruvian tar pit, reconstructing the biodiverse Ice Age ecosystem and investigating how it changed into the barren desert it is today. This ecosystem collapse occurred during a time of climate changes and human impacts similar to those happening now. It is hoped that studying these past changes can help prevent future extinctions. This project will engage North- and South American students and scientists in recovering, identifying, and describing fossil material from a north-coastal Peruvian asphaltic locality (colloquially, “tar pit”). The curated flora and fauna, comprising plant, small vertebrate, and invertebrate remains, will form a comprehensive and scientifically valuable late-Quaternary fossil collection in this poorly-studied region, and will be analyzed to investigate interactions between humans, climate, and biotic communities. This research will focus on three main questions: (1) What was the late-Quaternary ecosystem structure in the coastal western Neotropics, before the disappearance of the Pleistocene large mammal communities?; (2) How, when, and in response to what climatic and anthropogenic processes did this ecosystem undergo the dramatic ecological state change to its current desertified condition?; and, (3) How did these processes integrate with environmental changes and anthropogenic impacts in other South American regions, leading to a continental – and global – extinction event?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.