What Happened to the Dinosaurs?

Timothy Rowe

Thursday, 23 Apr 2015 at 7:00 pm – South Ballroom, Memorial Union

Timothy Rowe is a paleontologist whose research focuses on the evolution and development of vertebrates. He is the J. Nalle Gregory Regents Professor of Geology at University of Texas, Austin, as well as director of the Vertebrate Paleontology Laboratory, which holds one of the largest research collections of vertebrate fossils in America. Co-founder and director of the High-Resolution X-ray Computed Tomography Facility, he is a leader in developing digital technologies to analyze and visualize the skeleton along with the soft tissues that the skeleton supports. His research has been supported by the National Science Foundation, the Keck and Intel Foundations, and the American Chemical Society. Phi Beta Kappa Lecture

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Abstract
A great extinction event reshaped much of Earth’s biota 65 million years ago. Early attempts to explain the event, for example invoking alien invaders from outer space, were vague and unscientific. But with the emergence of Plate Tectonic Theory in the 1970s, we at last had a credible, testable mechanism that may have driven the event. Huge volcanic flood basalts cover large regions of the southern hemisphere, and their age and chemistry leave little doubt that a rare episode of extreme volcanic activity occurred in the half-million years leading up to the extinction, with serious environmental effects. Problem solved? Probably not.

Scientists in the 1980s discovered evidence of a major asteroid impact that coincided in time with the extinction, and it too had serious environmental effects. Problem solved? Probably not.

Looking at the other major extinctions in Life history over the last billion years it appears that multiple factors conspired and converged on each of the great events. Making things even more difficult, we are still struggling to understand just exactly what parts of Earth’s biota became extinct and why the surviving lineages survived. In the shadow of debate over volcanism vs. asteroid impact, dinosaurs are the quintessential example of scientific concepts evolving in light of avalanches of new information. Whereas some of the dinosaurs indeed disappeared 65 million years ago, we can now trace the dinosaurian ancestry of living birds in minute detail. Exceptionally preserved fossils record the origin of feathers and flight, and above all the evolution of large brains that rival our own in size and behavioral complexity. The survival of avian dinosaurs to encounter creatures with the biggest brains ever, just a few thousand years ago, is a lesson on the rise and fall of evolutionary innovation, one as portentous as the extinction itself.

Cosponsored By:

• Geological & Atmospheric Sciences
• Phi Beta Kappa
• Committee on Lectures (funded by Student Government)