What really Killed the dinosaurs? 

Ammonites, pterosaurs, plesiosaurs, and most famously, dinosaurs, are just a small percentage of the 75% of species that went extinct at the Cretaceous-Paleogene boundary. What caused this mass extinction? Was it a giant meteor impact? Massive outpourings of lava and gas? Or something else all together? Join Ph.D. student, Courtney Sprain, as she walks you through the very Berkeley-centric history of the of the mass extinction at the Cretaceous-Paleogene boundary and how current UC-Berkeley scientists are employing new techniques to further understand what really killed the dinosaurs.

 

Courtney Sprain works at the Berkeley Geochronology Center with Paul Renne on late Cretaceous Earth history, as well as on the records of late Mesoproterozoic paleogeography and paleointensity from the North American Midcontinent Rift in the UC Berkeley Paleomagnetism Lab.

A lost world: the South American megafauna and its extinction at the end of the last Ice Age

At the end of the last ice age (about 12,000 years ago) the world saw the extinction of most of its big size mammals, event known as the late Quaternary Extinction Event. In South America this extinction was more severe when compared with any other continent and around an 82% of the big mammals that inhabited that continent disappear forever. According to the chronologies of extinction known until today, these events happened close in time with the arrival of the first human populations into the American continent and also near the time of the major climate changes that occurred during the transition from the last Ice Age to the present climatic conditions. For this reason these two factors, humans and climate, have been historically placed as the most plausible causes behind these extinctions.

 

Natalia Villavicencio is interested in how biological communities have responded to large-scale environmental changes in the past. She is particularly interested in organisms’ responses to the climate change that occurred during the last Glacial-Interglacial transition. “I have always been interested in the history of life. My previous research was focused on plant community change due to precipitation and climate during the last 50,000 years. Now, in the Barnosky Lab, I’m really enthusiastic about seeing how mammal communities have responded and adapted to past environmental changes.”