RUI/SG: Phylogenetic Relationships of Archaic "Ungulates" and Their Implications for the Timing and Rate of Divergence of Placental Mammal Clades

RUI/SG：古代“有蹄类动物”的系统发育关系及其对胎盘哺乳动物进化枝分化时间和速率的影响

• 批准号: 1456826
• 负责人: Luke Holbrook
• 金额: $ 14.98万
• 依托单位: Rowan University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-07-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1456826&HistoricalAwards=false
• 关键词: RUI; SG; Phylogenetic; Relationships; Archaic

"Condylarths" are a collection of different families of fossil mammals that lived during the first 20 million years or so after the extinction of the dinosaurs. Different kinds of condylarths have been considered to be ancestors or close relatives of certain early lineages of mammals, especially the various groups of hoofed mammals. Recent studies using DNA from living mammals have given us a better understanding of how the different lineages of living mammals evolved, but they have also made the relationships of the condylarths less clear. This research aims to clarify how condylarths are related to other mammals, particularly those lineages that have survived to the present. Because they lived during a time when the various lineages of living mammals appeared in the fossil record, understanding the evolutionary relationships of condylarths to living mammals will help us better understand the origins of different mammal lineages. This will help resolve a longstanding issue as to whether most mammal lineages diversified after the dinosaurs went extinct or well before the dinosaur extinction (as some DNA studies of mammals have proposed). As a result, it will help us understand the reasons why mammals diversified into so many forms that we see today, including our own species.This study will focus specifically on four topics: 1) the phylogenetic affinities of condylarth taxa to extant mammalian lineages; 2) whether any condylarth families form natural (monophyletic) groups; 3) whether ungulates (hoofed mammals) are a natural group; and 4) how condylarth evolution affects the interpretation of divergence times for various mammal lineages. Data from the skeletal anatomy of condylarths will be combined with morphological and molecular data for a broad range of extant and extinct placental mammals. Parsimony, likelihood, and Bayesian methods will be used to evaluate the phylogenetic positions of condylarths, and several new approaches and methods will be used to estimate divergence times. The results will assess the phylogenetic position and taxonomy of condylarth taxa, re-evaluate the significance of condylarths for the origins of placental mammal lineages, and re-evaluate divergence times of extant placental lineages based on condylarth phylogeny.

“髁突”是不同家族的哺乳动物化石的集合，它们生活在恐龙灭绝后的头2000万年左右。不同种类的髁状突被认为是某些早期哺乳动物谱系的祖先或近亲，特别是各种有蹄类哺乳动物。最近的研究使用来自活的哺乳动物的DNA，使我们更好地了解不同谱系的哺乳动物进化，但他们也使髁状突的关系不太清楚。这项研究旨在阐明髁突与其他哺乳动物的关系，特别是那些存活至今的谱系。由于它们生活在化石记录中出现各种哺乳动物谱系的时代，因此了解髁突与哺乳动物的进化关系将有助于我们更好地了解不同哺乳动物谱系的起源。这将有助于解决一个长期存在的问题，即大多数哺乳动物的谱系是在恐龙灭绝之后还是在恐龙灭绝之前（正如一些哺乳动物的DNA研究所提出的那样）多样化。本研究将着重于四个方面：1）髁突动物类群与现存哺乳动物谱系的亲缘关系; 2）髁突动物家族中是否有自然形成的; 3）髁突动物家族中是否有自然形成的髁突动物; 4）髁突动物家族中是否有自然形成的髁突动物。（单系）类群; 3）有蹄类动物（有蹄哺乳动物）是否是一个自然类群; 4）髁突进化如何影响对各种哺乳动物谱系分歧时间的解释。髁突的骨骼解剖学数据将与广泛的现存和灭绝的胎盘哺乳动物的形态和分子数据相结合。简约，似然，贝叶斯方法将被用来评估髁状突的系统发育位置，和一些新的途径和方法将被用来估计分歧时间。研究结果将评估髁状突分类群的系统发育位置和分类，重新评估髁状突对于胎盘哺乳动物谱系起源的意义，并重新评估基于髁状突发育的现存胎盘谱系的分歧时间。