A Non-amniote Perspective on the Recovery from the End-Permian Extinction at High Latitudes: Paleobiology of Early Triassic Temnospondyls from Antarctica

大约2.52亿年前，一次大规模的物种灭绝使地球上90%以上的物种灭绝。 与这次灭绝同时发生的是，盘古大陆的南极部分过渡到了一个没有永久冰盖的温暖气候状态。 与低纬度地区相比，人们对南极洲大灭绝幸存者的了解相对较少，尽管有人假设南极洲更靠近极地的位置使其免受最严重的灭绝影响。 作为NSF赞助的2017/2018年深野外营地的结果，在沙克尔顿冰川地区的岩石中发现了一批引人注目的脊椎动物化石。 该系列包括从南极洲发现的保存最完好和最完整的两栖动物化石材料，其中包括两种以前未描述的物种。 该基金支持一位具有化石两栖动物专业知识的博士后研究人员描述和解释这些化石的重要性，包括它们的识别，关系以及它们如何适应南极洲和其他南半球陆地生态系统的陆地组合鉴于灭绝后环境的重大重组。 作为这项工作的一部分，还将审查两栖动物化石的历史收藏。 华盛顿大学的本科生将积极参与这项研究，并学习硬组织组织学和CT数据处理等技能。 公众参与南极科学将在华盛顿大学伯克博物馆完成，该博物馆是华盛顿州立自然历史和文化博物馆。 特别是，一个新的展览南极两栖动物将被开发作为古生物画廊的一部分，每年有超过100，000名游客参观。技术摘要这个为期两年的项目将研究三叠纪temnospondyls的进化基于最近从南极洲沙克尔顿冰川地区发现的一个显着的化石收藏。 从Fremouw组中段采集的Temnospondyls是该地层间隔中第一批可识别的四足动物化石的一部分。对这些化石进行彻底的解剖学描述和比较将增加新的动物群信息，并有助于确定该层位的年龄是早三叠世还是中三叠世。 从下Fremouw组保存完好的temnospondyl材料将允许更精确的识别比以前可能的，并将提供见解的最早阶段，他们的辐射在灭绝恢复间隔。 总的来说，首席研究员和博士后研究员将带头努力修改南极成员Temnospondyli的系统学，并在三叠纪四足动物进化的框架内适当地将它们置于背景中。 研究小组还将利用两栖动物化石对气候敏感的性质，通过对选定的化石进行组织学分析，更好地了解中生代早期高纬度地区的季节性模式。 初步数据表明，temnospondyls异常多样性和高度地方性的二叠纪末灭绝后，立即相比，他们的分布之前和之后的这段时间。 如果得到证实，这种宏观进化模式可以用来预测现代两栖动物对未来气候扰动的反应。 总的来说，这项研究将为Fremouw组的脊椎动物群提供新的见解，并阐明在二叠纪-三叠纪大灭绝之后盘古大陆南部陆地生态系统的演变。 作为更广泛影响的一部分，该研究小组将帮助开发一个展览，展示南极洲保存最完好的一些化石，向公众解释古生物学家如何利用化石和岩石来了解过去的气候，如三叠纪的“热-该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准。

Non-technical AbstractAround 252 million years ago, a major mass extinction wiped out over 90% of species on Earth. Coincident with this extinction, the Antarctic portion of the supercontinent of Pangea transitioned to a warmer climatic regime devoid of a permanent ice cap. Compared to lower latitudes, relatively little is known about the survivors of the extinction in Antarctica, although it has been hypothesized that the continents more polar location shielded it from the worst of the extinctions effects. As the result of a NSF-sponsored deep field camp in 2017/2018, a remarkable collection of vertebrate fossils was discovered in the rocks of the Shackleton Glacier region. This collection includes the best preserved and most complete materials of fossil amphibians ever recovered from Antarctica, including two previously undescribed species. This grant supports one postdoctoral researcher with expertise in fossil amphibians to describe and interpret the significance of these fossils, including their identification, relationships, and how they fit into the terrestrial ecosystem of Antarctica and other southern hemisphere terrestrial assemblages in light of the major reorganization of post-extinction environments. Historical collections of fossil amphibians will also be reviewed as part of this work. Undergraduate students at the University of Washington will be actively involved as part of this research and learn skills like hard tissue histology and CT data manipulation. Public engagement in Antarctic science will be accomplished at the University of Washington Burke Museum, which is the Washington State museum of natural history and culture. Specifically, a new exhibit on Antarctic amphibians will be developed as part of the paleontology gallery, which sees over 100,000 visitors per year.Technical AbstractThis two-year project will examine the evolution of Triassic temnospondyls based on a remarkable collection of fossils recently recovered from the Shackleton Glacier region of Antarctica. Temnospondyls collected from the middle member of the Fremouw Formation are part of the first collection of identifiable tetrapod fossils from this stratigraphic interval. Thorough anatomical description and comparisons of these fossils will add new faunal information and also aid in determining if this horizon is Early or Middle Triassic in age. Exquisitely preserved temnospondyl material from the lower Fremouw Formation will permit more precise identification than previously possible and will provide insights into the earliest stages of their radiation in the extinction recovery interval. Overall, the Principal Investigator and Postdoctoral Researcher will spearhead an effort to revise the systematics of the Antarctic members of Temnospondyli and properly contextualize them in the framework of Triassic tetrapod evolution. The research team will also take advantage of the climate-sensitive nature of fossil amphibians to better understand patterns of seasonality at high-latitudes during the early Mesozoic by subjecting selected fossils to histological analysis. Preliminary data suggest that temnospondyls were exceptionally diverse and highly endemic immediately after the end-Permian extinction, when compared to their distribution before and after this interval. If confirmed, this macroevolutionary pattern could be used to predict the response of modern amphibians to future climate perturbations. Overall, this research will provide new insights into the vertebrate fauna of the Fremouw Formation, as well as shed light on the evolution of terrestrial ecosystems in southern Pangea in the wake of the Permian-Triassic mass extinction. As part of the broader impacts, the research team will help to develop an exhibit featuring some of the best preserved fossils from Antarctica to explain to the public how paleontologists use fossils and rocks to understand past climates like the Triassic 'hot-house' world that lacked permanent ice caps at the poles.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.