“What Really Killed the Dinosaurs?”

In his lecture “What Really Killed the Dinosaurs?” Mark Richards, provost and professor of Earth and Space Sciences at the University of Washington, will discuss the two leading theories for the demise of T. rex and friends: meteor impact and volcanism. The disappearance of the dinosaurs and most other species in the fossil record 66 million years ago is widely attributed to the Chicxulub meteor impact in Yucatán, Mexico. However, at the same time, some of the largest volcanic eruptions in Earth history, the Deccan Traps, were occurring in India — a coincidence that has confounded geologists for three decades. New evidence, especially high-precision radio isotopic dating of the Deccan lavas, now suggests that the Chicxulub impact accelerated the Deccan Traps eruptions right at the time of the dinosaurs’ extinction. Therefore, we do not yet know whether T. rex and friends were exterminated mainly by the impact itself or by the impact-triggered Deccan eruptions, since both events may have affected the environment in similar ways. “As an Earth scientist, I have spent most of my career researching the fundamental nature of plate tectonics, large-scale volcanism, and, most lately, the causes of mass extinction,” Richards said. A geophysicist, Richards holds a faculty appointment in the College of the Environment’s Department of Earth and Space Sciences. As provost and executive vice president for academic affairs, he is the University’s chief academic and budget officer.