Doctoral Dissertation Research: Comparative paleoecology of three contemporaneous Early Miocene catarrhine sites in East Africa

什么时候化石遗址上没有一个物种真的意味着该物种不在一个曾经活着的群落中？这个问题将通过对东非灵长类化石记录的比较研究来解决。东非2100万年前至1700万年前(中新世早期)的化石记录中包含了丰富的早期卡特拉斯动物(包括猴子、猿猴和人类在内的哺乳动物群体)的遗骸。东非的Songhor、Koru和Napak化石遗址包含不同的卡他物种组合，尽管在空间和时间上非常接近(1900万到2000万)。有些物种在所有地点都有发现，而另一些物种只在一个地点发现。本论文研究的目的是解释这些差异，并了解它们的生态意义。以前有人提出，这些不同的卡特拉犀类分布是这些地区在中新世期间栖息地差异的结果。如果这是真的，我们预计会在其他哺乳动物动物群中发现类似的差异。卡特龙的差异是由于栖息地的差异，这一假说将通过对这三个地点的卡他哺乳动物和非卡他哺乳动物化石的比较研究来检验。此外，还将测试为什么这些卡他鼻组合可能不同的其他原因。这些偏差包括：(1)采样偏差，(2)保存或蚕茧学偏差，以及(3)化石采集偏差。这些因素中的每一个都可以在很大程度上改变化石组合的组成，即使化石起源的生物群落是相同的。因此，对这些因素的测试在任何试图了解区际差异的古生物研究中都是至关重要的。最后，关于现代非洲卡他龙群落分布的数据将被用来创建卡特拉犀类在中新世化石记录中的分布模型。这项研究既重要又有趣，因为正在研究的卡特龙化石代表了猴子-猿类-人类谱系中最早的成员，包括已知的最早的猴子和特征良好的最早的猿类。对这些化石及其相关动物群的进一步研究将加深我们对早中新世灵长类生态差异的理解。这将对理解卡他鼻进化的后期阶段，包括我们自己的物种进化具有重要的意义。特别是，这项研究将强调采样偏差对化石记录的重要影响，这是一个在古人类学研究中很少涉及的话题。此外，这项研究将在生物科学中具有更广泛的意义，因为它将结合古生物学和生态学领域的方法。该项目的更广泛影响是，它将鼓励与肯尼亚国家博物馆和乌干达博物馆的研究人员开展国际合作。通过促进非洲研究人员积极参与这一项目，解决了传统上代表性不足的群体的纳入问题。收集到的所有化石数据将被整合到目前正在设计的肯尼亚国家博物馆数据库中，以便这些数据可以广泛传播给其他研究人员。此外，研究结果将发表在同行评议的期刊上，并在科学会议上公布。

When does absence of a species at a fossil site truly mean that the species was absent from a once living community? This question will be addressed by a comparative study of the East African primate fossil record. The East African fossil record between 21 and 17 million years ago (Early Miocene) contains abundant remains of early catarrhines (the mammalian group that includes monkeys, apes, and humans). The fossil sites of Songhor, Koru, and Napak in East Africa contain different combinations of catarrhine species, despite being very close in space and time (19-20 million). Some species are found at all sites, while others are found at only one. The goal of this dissertation research is to explain these differences and to understand their ecological significance. It has previously been proposed that these different catarrhine distributions are the result of habitat differences between these areas during the Miocene. If this were true, we would expect to find similar differences recorded in the rest of the mammalian fauna. The hypothesis that catarrhine differences are due to habitat differences will be tested through a comparative study of both the catarrhine and non-catarrhine mammalian fossils from these three sites. In addition, alternative reasons why these catarrhine assemblages might vary will also be tested. These include: (1) sampling bias, (2) preservational or taphonomic biases, and (3) fossil collecting biases. Each of these factors can substantially alter the composition of fossil assemblages, even if the living communities from which the fossils derived were identical. Therefore, testing for these factors is critical in any paleontological study that seeks to understand interlocality variation. Finally, data on the distributions of modern African catarrhine communities will be used to create models of what catarrhine distributions should look like in the Miocene fossil record. This research is important and interesting because the catarrhine fossils under study represent the earliest members of the monkey-ape-human lineage, including the earliest known monkey, and the earliest well-characterized ape. Further study of these fossils and their associated faunas will increase our understanding of the ecological differences among Early Miocene primates. This will have important implications for understanding later stages of catarrhine evolution, including that of our own species. In particular, this study will highlight the important effects that sampling biases have on the fossil record, a topic that is only rarely addressed in paleoanthropological research. Also, this research will have significance more widely in the biological sciences because it will incorporate methods from the fields of both paleontology and ecology. The broader impact of this project is that it will encourage international collaboration with researchers at the National Museums of Kenya and the Uganda Museums. Inclusion of traditionally underrepresented groups is addressed by promoting the active involvement of African researchers in this project. All fossil data collected will be integrated into the National Museums of Kenya database currently being designed so that the data can be disseminated widely to other researchers. In addition, results will be published in peer-reviewed journals and presented at scientific conferences.