DISSERTATION RESEARCH: Geographic complexity in the recovery of terrestrial vertebrate assemblages from mass extinction

这个项目将提高我们对陆地生命在过去5亿年最大的灭绝事件后如何多样化的理解。这一事件发生在2.52亿年前的二叠纪和三叠纪之间，当时超过70%的陆生动物灭绝了。化石记录是许多有关地球生命历史问题的主要资料来源之一。对于二叠纪末期的事件，我们对陆地上发生的事情的了解几乎完全来自两个地方——俄罗斯和南非。这项新的研究将为另外两个地方——坦桑尼亚和赞比亚——的陆生脊椎动物的化石材料建立一个数据库。在灭绝之前，这两个新地点的化石群落与南非的化石群落相似，但在灭绝之后，它们就大不相同了，而且包括了新的动物，比如哺乳动物的近亲，令人惊讶的是，还有第一批恐龙的早期近亲。这项研究将把从最近的研究中收集到的数据与欧洲和非洲博物馆中储存的数据结合起来，开发出最广泛的二叠纪末陆地动物化石数据库。这将使古生物学家能够确定这一时期比以往任何时候都大的地区的多样化模式，并发现特定物种在有史以来最大规模的物种灭绝事件中幸存下来并随后繁荣起来的原因。该项目将综合陆地四足动物多样性的几个方面，包括物种丰富度、均匀度、相对丰度、营养结构和生态位多样性，并增加坦桑尼亚和赞比亚（TZAM）采样不足盆地的地理复杂性的新组成部分。近年来在那里进行的大量实地考察证实，沉积岩可以与南非和俄罗斯的沉积岩相关联，因此可以作为关于灭绝和恢复过程的假设的独立测试。初步数据表明，在灭绝事件发生前，TZAM和南非之间存在同质动物群，但在恢复过程中，生态系统破碎化，导致地方性和生物地理分化程度增加。该项目旨在测试与二叠纪末灭绝两侧盆地内和盆地之间脊椎动物群落的生态结构和生物地理模式有关的假设。此外，研究人员还将深入研究一个针对现存物种的生态假说，即丰度-范围假说。

This project will improve our understanding of how terrestrial life diversified after the largest extinction event of the last 500 million years. This event took place just over 252 million years ago at the boundary between the Permian and Triassic periods, when more than 70% of terrestrial animals went extinct. The fossil record is one of the main sources of data for many questions concerning the history of life on Earth. For the end-Permian event, our understanding of what occurred on land is known almost entirely from just two places - Russia and South Africa. This new research will build a database of fossil material belonging to terrestrial vertebrate animals from two additional places - Tanzania and Zambia. Before the extinction the fossil communities at those two new locations were similar to those of South Africa, but afterwards they were very different, and included new animals such as close relatives of mammals and, surprisingly, early relatives of the first dinosaurs. This research will combine data collected from recent research with that stored in museums across Europe and Africa to develop the most extensive fossil database of end-Permian land animals. This will allow paleontologists to determine diversification patterns across a larger region than has ever been done for this time period, and to discover the reasons that particular species survived the largest mass extinction event of all time and subsequently thrived. This project will synthesize several facets of diversity among terrestrial tetrapods, including species richness, evenness, relative abundances, trophic structure, and ecological niche diversity, and adds a new component of geographical complexity from poorly-sampled basins in Tanzania and Zambia (TZAM). Substantial fieldwork there in recent years has confirmed that the sedimentary rocks can be correlated with those of South Africa and Russia, and can therefore act as independent tests of hypotheses about the extinction and recovery processes. Preliminary data indicate that a homogeneous fauna existed between TZAM and South Africa before the extinction event, but that during the recovery process ecosystems fragmented, resulting in increased levels of endemism and biogeographic differentiation. This project aims to test hypotheses related to ecological structure and biogeographic patterns of vertebrate communities on either side of the end-Permian extinction, both within and between basins. Additionally, the researchers will test in deep time an ecological hypothesis developed for extant species, the abundance-range hypothesis.