Dining after the dinosaurs? Dietary diversity and niche partitioning in Palaeocene mammals

该项目将使用新技术来解决古生物学中的一个长期问题：恐龙及其灭绝对哺乳动物进化史的影响。最近的一些研究集中在哺乳动物多样化的时间（例如Wilson et al. 2012，Close et al. 2015，Grossnickle 2019），但更难测试生态多样性的假设。对侏罗纪时期保存完好的有关节哺乳动物骨骼的形态学分析开始描绘出哺乳动物占据比以前认为的更广泛的生态位的画面，但大多数哺乳动物化石仅从脱节的遗骸和牙齿中了解，并且不适合这种类型的功能分析。因此，在何种程度上，他们的生态多样性受到影响的K-Pg灭绝，以及在古新世的生态多样性的模式，一直是难以解决的问题。该项目将采用一种强大的新方法，即牙科微磨损纹理（DMT）分析，该方法在早期哺乳动物中的应用是由监督员开创的（Purnell等人2013，Gill等人2014）。你将结合联合收割机这与其他饮食代理（同位素数据，mesowear和牙齿的定量形状分析）在系统发育的背景下，进行多学科，多代理的古新世哺乳动物的饮食多样性的调查，和营养生态位占领和分区的模式。你将建立现代哺乳动物谱系的早期成员所属的饮食行会。DMTA揭示了侏罗纪哺乳动物中隐藏的营养多样性，表明哺乳动物进化最早阶段的谱系分裂与生态形态专业化和生态位分配相关（Gill等人，2014）。该项目将该方法应用于古新世化石，同样将产生对哺乳动物进化史的新见解。该项目非常适合具有地质或生物科学学士学位并具有定量分析能力的申请人。在莱斯特，你将加入一个充满活力的研究小组，博士和硕士研究生致力于化石脊椎动物的饮食和营养生态位的新分析。方法：该项目将重点关注来自新墨西哥州圣胡安盆地的材料-世界上最重要的古新世哺乳动物化石地点之一。这些收藏品在新墨西哥州自然历史博物馆展出，其中包括监督人员最近挖掘的新材料，该项目为在新墨西哥州进行实地考察提供了机会。饮食分析将采用莱斯特开发的多变量方法进行定量3D牙科微磨损纹理分析（Purnell等人，2013; Gill等人，2014）。结合这与分析牙齿mesowear，同位素数据，牙齿地形，功能形态学，和定量系统发育的方法将允许强大的分析和假设检验的作用，喂养和饮食在不同的时间和空间尺度。这种方法将允许饮食假设的独立测试，并在更广泛的饮食行业协会的特定角色的评估，并有可能拿起饮食transtions，早于和潜在的驱动牙齿形态适应新的功能roles.Training和技能：学生将被授予CENTA 2培训学分（CTC）参加CENTA 2提供的和“自由选择”的外部培训。一个CTC相当于0.5天的课程，学生必须在博士学位的三年内积累100个CTC。专家培训将包括牙齿微磨损纹理分析，牙齿地形分析，系统发育测试和宏观进化模式分析技术，以及古近纪哺乳动物的解剖分析。重点将放在稳健的定量分析和统计假设检验上。

OverviewThis project will use new techniques to address one of the perennial questions in palaeontology: the impact of dinosaurs and their extinction on mammal evolutionary history. A number of recent studies have focussed on the timing of mammal diversification (e.g. Wilson et al. 2012, Close et al. 2015, Grossnickle 2019), but it is more difficult to test hypotheses of ecological diversity. Morphological analysis of well-preserved articulated mammal skeletons of Jurassic age is starting to paint a picture of mammals occupying a broader range of ecological niches than previously thought, but the majority of fossil mammals are known only from disarticulated remains and teeth, and are not amenable to this type of functional analysis. Consequently, the degree to which their ecological diversity was affected by the K-Pg extinction, and the pattern of ecological diversification during the Palaeocene, have been difficult issues to address. This project will employ a powerful new approach, analysis of Dental Microwear Texture (DMT), the application of which to early mammals was pioneered by the supervisors (Purnell et al. 2013, Gill et al. 2014). You will combine this with other dietary proxies (isotopic data, mesowear and quantitative shape analysis of teeth) in phylogenetic context, to conduct multidisciplinary, multiproxy investigation of the dietary diversity of Palaeocene mammals, and of the patterns of trophic niche occupation and partitioning. You will establish the dietary guilds to which the early members of modern mammal lineages belong. DMTA has revealed hidden trophic diversity in Jurassic mammals, indicating that lineage splitting during the earliest stages of mammalian evolution was associated with ecomorphological specialization and niche partitioning (Gill et al. 2014). This project, applying the approach to Palaeocene fossils, will similarly yield new insights into the evolutionary history of mammals.This project is ideal for applicants with a first degree in geological or biological sciences and an aptitude for quantitative analysis. At Leicester you will join a dynamic group of researchers, PhD and Masters students working on novel analyses of diet and trophic niche in fossil vertebrates.Methodology: The project will focus on material from the San Juan Basin of New Mexico - one of the world's premier localities for Palaeocene mammal fossils. The collections, held in the New Mexico Museum of Natural History, include new material recently excavated by the supervisors, and the project offers opportunities for fieldwork in New Mexico. Dietary analysis will employ quantitative 3D Dental Microwear Texture Analysis using multivariate methods developed at Leicester (Purnell et al. 2013, Gill et al. 2014). Combining this with analysis of tooth mesowear, isotopic data, dental topography, functional morphology, and quantitative phylogenetic methods will allow robust analysis and hypothesis testing of the role of feeding and diet at different temporal and spatial scales. This approach will allow independent testing of dietary hypotheses, and evaluation of specific roles within broader dietary guilds, and has the potential to pick up dietary transtions that predate and potentially drive morphological adaptation of teeth to new functional roles.Training and skills:Students will be awarded CENTA2 Training Credits (CTCs) for participation in CENTA2-provided and 'free choice' external training. One CTC equates to 0.5 day session and students must accrue 100 CTCs across the three years of their PhD. Specialist training will include dental microwear texture analysis, dental topographic analysis, techniques for phylogenetic testing and analysis of macroevolutionary patterns, and anatomical analysis of Cretaceous-Paleogene mammals. The emphasis will be on robust quantitative analysis and statistical hypothesis testing.