CAREER: Taphonomy and Evolution of Theropod Dinosaur Reproduction

兽脚类恐龙繁殖的分类和进化在产蛋率、蛋的大小和形状、蛋壳的微观结构、巢形式、孵化方法以及父母照料的方式和普遍程度等方面，现存鸟类的繁殖与其他现代脊椎动物的繁殖有明显的不同。鸟类和其他现存脊椎动物之间的差异引发了这样一个问题：这种独特的生殖方式是如何以及何时进化出来的。它是在实现飞行之前还是之后产生的？鸟类进化而来的食肉兽脚类恐龙是与它们的恐龙近亲更相似，还是与现代鸟类更相似？中生代恐龙的繁殖和生活史策略对它们的成功有多重要？这项拟议的研究通过记录中生代从恐龙到鸟类的生殖特征的进化来解决这些问题。调查包括四个阶段：1)研究现代鸟类和鳄鱼的筑巢地点，以帮助解释恐龙地点的属性；2)白垩纪兽脚类恐龙筑巢地点的调查；3)基于野外、实验室和博物馆研究建立生殖特征进化史；4)比较兽脚类恐龙、其他恐龙和活生生的产卵脊椎动物的生活史策略。这项研究的优势包括一个跨学科的团队，他们在化石保存研究、蛋壳结构和现代鸟类的筑巢行为方面拥有专业知识，以及一套无与伦比的现代和化石样本。现代筑巢地点既代表鳄鱼，也代表表现出广泛繁殖行为的鸟类。中生代恐龙样本包括来自蒙大拿州和爱达荷州白垩纪的四种蛋类型；这四种蛋类型代表了北美唯一的原地兽脚类恐龙蛋。现代筑巢视野的研究为解释化石的筑巢地点提供了框架。对现代鳄鱼和鸟类的研究产生的数据将有助于识别影响化石保存的模式和过程。结合广泛的田野调查、蛋的实验室分析和特殊的化石样本，将为兽脚类恐龙的蛋保存和繁殖行为提供新的见解。识别新的卵子特征和解决关于兽脚类繁殖行为的争议问题将加强我们对进化的理解。记录鸟类及其兽脚类恐龙祖先的生殖进化史，将为了解鸟类的起源提供洞察力。比较鳄鱼、恐龙和鸟类的现代和灭绝的生活史策略将增加对恐龙生态学的当前理解，在宏观进化尺度上测试生活史理论，并允许评估可能有助于恐龙在整个中生代取得整体成功的因素。教育目标包括将研究、观察和解释纳入大学课程，并通过讲习班和实地考察参与蒙大拿州农村科学教师的专业发展。此外，该项目还将支持两名硕士和八名本科生的研究机会。最后，瓦里奇奥担任将于2009年夏天在蒙大拿州立大学举行的第四届恐龙蛋和恐龙蛋和恐龙宝宝国际研讨会的主办委员会主席。这次会议为传播研究成果提供了一个极好的机会，同时促进了生物学家和古生物学家之间就鸟类和恐龙繁殖的进化更多地交流意见。

TAPHONOMY AND EVOLUTION OF THEROPOD DINOSAUR REPRODUCTION David J. Varricchio Reproduction in living birds differs markedly from that of other modern vertebrates in the rate of egg production, egg size and shape, microscopic structure of the eggshell, nest form, method of incubation, and the manner and prevalence of parental care. The disparity between birds and other living vertebrates raises questions as to how and when this unique reproductive style evolved. Did it originate before or after the achievement of flight? Were the carnivorous theropod dinosaurs from which birds evolved reproductively more similar to their dinosaur relatives or to modern birds? How important were the reproductive and life history strategies of Mesozoic dinosaurs to their success? The proposed research addresses these questions by documenting the evolution of reproductive traits through the Mesozoic from dinosaurs to birds. The investigation consists of four phases: 1) study of modern bird and crocodile nesting localities for attributes that would help interpret dinosaur sites, 2) investigation of Cretaceous theropod dinosaur nesting sites, 3) construction of an evolutionary history of reproductive traits based on field, laboratory, and museum study and 4) comparison of the life history strategies among theropod dinosaurs, other dinosaurs, and living egg-laying vertebrates. Strengths of this study include an interdisciplinary team with expertise in taphonomy (the study of fossil preservation), eggshell structure, and the nesting behavior of modern birds, as well as an unsurpassed suite of modern and fossil samples. Modern nesting localities represent both crocodilians and birds that exhibit a wide array of reproductive behaviors. The Mesozoic dinosaur sample includes four egg types from the Cretaceous of Montana and Idaho; these four egg types represent the only in place theropod dinosaur eggs from North America. The study of modern nesting horizons provides the framework for interpreting fossil nesting localities. Data generated from the studies of modern crocodilians and birds will allow recognition of patterns and processes affecting fossil preservation. The combination of extensive fieldwork, laboratory analysis of eggs, and the exceptional fossil sample will provide new insights on egg preservation and the reproductive behavior of theropod dinosaurs. Identification of new egg characters and resolution of controversial issues regarding theropod reproductive behavior will strengthen our evolutionary understanding. Documentation of the evolutionary history of reproduction in birds and their theropod dinosaurs ancestors, will provide insight into the origination of birds. Comparison of modern and extinct life history strategies among crocodilians, dinosaurs, and birds will increase current understanding of dinosaur ecology, test life history theory on a macroevolutionary scale, and permit evaluation of factors potentially contributing to the overall success of dinosaurs throughout the Mesozoic. Educational goals include incorporation of research observation and interpretation into university courses and professional development for rural Montana science teachers through workshops and fieldwork participation. Additionally, the project will support research opportunities for two masters and eight undergraduate students. Finally, Varricchio serves as host committee chair for the 4th International Symposium on Dinosaur Eggs and Babies to be held at Montana State University in the summer of 2009. This meeting provides an excellent opportunity for dissemination of the research results, while facilitating greater exchange of ideas between biologists and paleontologists regarding the evolution of bird and dinosaur reproduction.