The evolution of birds from theropod dinosaurs is one of the major evolutionary transitions in the history of life. This transition has emerged as a textbook example for understanding the origins of major groups, new body plans, and novel behaviors, thanks to a rapidly expanding fossil record of early birds and their closest dinosaurian relatives (the coelurosaurian theropods). Several outstanding questions remain, however, most notably regarding the phylogeny of birds and their closest relatives and the major macroevolutionary patterns in morphological evolution during the theropod-bird transition. This project aims to tackle both of these issues by integrating new data collection, phylogenetic analyses, and quantitative evolutionary modeling techniques. A large anatomical dataset will be used to derive a complete species-level phylogeny of Mesozoic coelurosaurs and to measure two major macroevolutionary metrics--rates of character change and anatomical disparity (variety in morphological features)--during the theropod-bird transition.
This project will result in better understanding of the evolutionary transition between carnivorous dinosaurs and birds, which is one of the few major transitions that is recorded in fine detail in the fossil record. This project will help train high school students as part of the American Museum of Natural History's Student Research Mentoring Program, involve the collaboration of undergraduate students beginning their careers in scientific research, and will be incorporated into public lectures, online data repositories, and a forthcoming book aimed at undergraduate and graduate students.
Birds evolved from carnivorous theropod dinosaurs, the group that includes Velociraptor and T. rex. This once controversial idea is now widely accepted and robustly supported by an ever-growing fossil record, including thousands of specimens of feathered dinosaurs from China. The evolution of small, flying birds from large, ground-living dinosaurs was one of the great evolutionary transitions in the history of life. It provides scientists a prime opportunity to study the origin of a major group and the evolution of a novel body type and way of life. This project aimed to better understand the transition between dinosaurs and birds. It funded the comprehensive anatomical descriptions of two theropod dinosaurs closely related to birds that are known from nearly complete and well-preserved skeletons, the tyrannosaurid Alioramus and the dromaeosaurid Balaur. It supported the compilation of a large database of 800+ anatomical features that varied in over 150 theropod dinosaurs and early birds, which were used to construct a phylogeny (family tree) placing birds in the context of dinosaur evolution and pinpointing which dinosaurs were the closest relatives of birds. In turn, this phylogeny was used to study major trends and rates in evolution across the theropod-bird transition, showing that the rise of birds was due to a dramatic increase in the speed of evolution. More broadly, this result supports a long-held theory about how evolution works: that the origins of major new groups and body types are associated with a surge in the rate of evolution. This grant resulted in over 10 peer-reviewed scientific publications, a comprehensive anatomical and phylogenetic dataset for early birds and close relatives, and new quantitative methods for studying major evolutionary trends. Results were also disseminated in a textbook written by the Co-PI and in 10+ public lectures given in North America and Europe. Two high school students and an undergraduate were mentored, and the Co-PI was able to travel to China, Russia, and South America to gather critical data and collaborate with foreign scientists.