EXPLORING MAJOR PATTERNS IN THE HISTORY OF ANIMAL LIFE

Roger Kaesler guided and shaped the Treatise on Invertebrate Paleontology during a crucial time in its history; the productivity of the Treatise during his tenure as head of the Paleontological Institute was extremely impressive. He insured the stability of the Treatise into the 21st century. Also, through Roger Kaesler's role as head of the Treatise he was involved in major paleontological initiatives conducted at the national and international levels. Ultimately, the Treatise serves as a tremendous repository of paleontological data bearing on the temporal and geographic distribution of various taxa; when these taxa are demonstrably monophyletic they represent unique components of the evolutionary tree of life. Studying evolutionary patterns at the grand scale of the history of life has become an important area of research in paleontology, and to a greater or lesser extent, depending on the particular study and the time periods and groups involved, the Treatise served as the ultimate foundation of the data bearing on these patterns. Here I intend to focus on some studies that the data from the Treatise have enabled, particularly as embodied in the “Sepkoski dataset.” In particular, I will use data bearing on fossil diversity to consider the extent to which patterns of animal evolution and extinction follow a random walk throughout the Phanerozoic; I will further explore the significance this has for our understanding of the evolutionary process. I will also present evidence and explore the significance of the fact that CO2 levels, proxies for climatic and tectonic change, also show an excellent correlation with the major patterns in the history of animal life. Finally, I will consider what these types of data can tell us about the nature of key episodes in the history of life, like the late Ordovician mass extinction.