Evolution and phylogenetic relationships of the early cerapodan dinosaurs

早期角足类恐龙的进化和系统发育关系

• 批准号: 2282291
• 金额: --
• 依托单位: University of Birmingham
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2019
• 资助国家: 英国
• 起止时间: 2019 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2282291
• 关键词: Evolution; phylogenetic; relationships; early; cerapodan

Cerapodans are a major group of herbivorous bipedal and quadrupedal ornithischian dinosaurs that dominated the terrestrial herbivorous niche during the Cretaceous. Early in their evolutionary history they split into two major groups, the ornithopods (duck-billed dinosaurs and their relatives) and the marginocephalians (horned and frilled dinosaurs and dome-headed dinosaurs). Subsequent to the split both groups radiated and developed complex chewing mechanisms and social structures that allowed them to achieve high diversity and abundance, and their fossils are well-known from outstanding material. However, early representatives of Cerapoda are known from much more fragmentary remains, and this has hindered our understanding of their taxonomy, relationships, and evolution. In particular, the ontogenetic status of many of the early cerapodans is unknown, and their fragmentary fossil record means that character transitions at the base of Cerapoda remain unclear. This has limited our interpretation of the evolution of mega-herbivory and quadrupedality in these dinosaurs. Competing phylogenetic hypotheses indicate radically different evolutionary relationships for early cerapodans, and it remains particularly unclear which taxa are included within Ornithopoda.The aim of this project is to conduct a comprehensive anatomical and systematic evaluation of all basal cerapodans and resolve phylogenetic uncertainties, providing a robust evolutionary tree. This tree will then be used to investigate the evolutionary history of Cerapoda with a focus on palaeobiogeography, diversity through time, and the timings of major divergences and radiations. Key research aims include: (1) resolving the taxonomy of key basal cerapodans, with a particular focus on North American Late Jurassic taxa; (2) examining the ontogenetic status and population ecology in a large sample of Early Cretaceous British taxa; (3) determining the phylogenetic position of basal cerapodans relative to the divergence of Ornithopoda and Marginocephalia; (4) using the resulting hypothesis to explore biogeographic and diversity patterns through time.

角足类是一个主要的食草性双足和四足鸟臀目恐龙，在白垩纪期间统治着陆生食草性生态位。在它们进化史的早期，它们分为两大类，鸟脚亚目（鸭嘴龙和它们的亲戚）和边缘头亚目（有角和皱褶的恐龙和圆顶头恐龙）。在分裂之后，这两个群体都辐射并发展了复杂的咀嚼机制和社会结构，使他们能够实现高度的多样性和丰富性，他们的化石因出色的材料而闻名。然而，角足动物的早期代表是从更零碎的遗骸中得知的，这阻碍了我们对它们的分类，关系和进化的理解。特别是，许多早期角足动物的个体发育状态是未知的，他们的零碎化石记录意味着角足动物底部的特征转变仍然不清楚。这限制了我们对这些恐龙中巨型食草动物和四足动物进化的解释。竞争的系统发育假说表明，从根本上不同的早期cerapodans的进化关系，它仍然是特别不清楚哪些类群包括在鸟足目，本项目的目的是进行全面的解剖和系统评价的所有基础cerapodans和解决系统发育的不确定性，提供一个强大的进化树。然后，这棵树将被用来调查Cerapoda的进化历史，重点是古生物地理学，随着时间的推移多样性，以及主要分歧和辐射的时间。主要研究目标包括：（1）解决了主要基足类的分类问题，特别是北美晚侏罗世的分类问题;（2）研究了大样本早白垩世英国分类群的个体发育状态和种群生态学;（3）确定了基足类相对于鸟足类和缘头类分歧的系统发育位置;（4）利用由此产生的假设，探索随时间推移的地理和多样性模式。