Paleobiology of Mio-Pliocene sharks, with emphasis on the extinct apex predator Carcharocles megalodon

I present here a dissertation that investigates aspects of Mio-Pliocene sharks using a macroecological approach and emphasizing in the extinction of the giant Carcharocles megalodon. I combine this research with a non-traditional component on educational technology where I describe the development of a blended learning tool. Because of this unusual component, this is a non-traditional dissertation.;Chapter 1 presents a general introduction. In Chapter 2 I describe the chondrichthyan fauna of the lower Miocene Culebra Formation of Panama and provide insight into Neotropical environments prior to the rise of the isthmus. This fauna is represented by 12 taxa and suggests a neritic environment positioned in the vicinity of emerged areas of the isthmus. In Chapters 3 to 5 I focus on the extinction of C. megalodon. In Chapter 3 I mathematically infer the date of extinction of this species. This result, combined with known macroevolutionary trends in potential prey, suggests that the modern gigantic sizes of filter-feeding whales was established after the extinction of C. megalodon. In Chapter 4 I study the body size trends of C. megalodon through its temporal and geographic range. The results provide evidence of a long-term selective pressure favoring larger individuals and stasis as a general mode of size evolution. I further use this study to provide a deep-time perspective on the body size trends of marine apex predators. In Chapter 5 I study the geographic distribution trends of C. megalodon over geologic time and propose that the decline of this species starts in the late Miocene. These results suggest that the collapse of this species may have been influenced by shifts in the diversity of filter-feeding whales (their potential prey), and the evolution of new competitors (toothed whales and the great white shark).;In Chapter 6 I describe the design and implementation of a blended course on the paleontology of Panama. This course had a unique combination of components that synergistically contributed to engage students with this field of science, and it can be applied to different disciplines and levels in students' training. Finally in Chapter 7 I provide the overall conclusions of this work.