DISSERTATION RESEARCH: Morphometric study of crocodylian cranial ecomorphology through phylogeny and ontogeny

鳄类在其8000万年的化石记录中表现出高度的颅骨变异和趋同。尽管进行了广泛的调查，形态学和分子生物学之间的差异仍然存在，并涉及到被认为反映了生态或功能专业化的细长颅形态的类群。利用几何形态测量学总结鳄鱼头骨的形态形状，该项目创建了第一个3-D鳄鱼头骨形态数据库的所有23个现存的鳄鱼孵化后个体发育和化石分类群从国家和国际收藏。该数据库的分析将：1）测试当前鳄鱼头骨形态的有效性及其与个体发育的关系，2）确定头骨形状分布如何与个体发育和个体发育相关，3）通过测试野生和养殖鳄鱼标本之间的头骨形状差异来确定形态可塑性和个体发育环境之间的关系。这项研究将提供深入了解模式和过程的形态进化，并有助于了解分子和形态系统发育假说鳄鱼之间的差异。通过这一项目产生的数据库将作为检验超出本提案目标的假设的基准。

Crocodylians exhibit a high degree of cranial variation and convergence throughout their 80 million-year fossil record. Despite extensive investigation, discrepancies between morphological and molecular phylogenies persist and relate to taxa that share a slender cranial morphology believed to reflect ecological or functional specialization. Using geometric morphometrics to summarize morphological shape in crocodilian skulls, this project creates the first 3-D crocodylian skull morphology database of all 23 extant crocodylian post-hatchling ontogenies and fossil taxa from national and international collections. Analyses of this database will: 1) test the validity of current crocodylian cranial morphology and their relationship to phylogeny, 2) determine how skull shape distributions are ontogenetically and phylogenetically related, 3) determine relationships between morphological plasticity and ontogenetic environment by testing for skull shape differences between wild and farmed alligator specimens through their ontogeny. This research will provide insights into patterns and processes underlying morphological evolution and help to understand the discrepancy between molecular and morphological phylogenetic hypotheses for crocodylians. The database generated through this project will serve as a benchmark for testing hypotheses beyond the objectives of this proposal.