FRS 001A (2 units) CRN 65610 T 4:10-6:00 pm
Dinosaur Extinction: Is the Asteroid-Impact Theory Ecologically Plausible?

Instructor: James Carey, Department of Entomology, College of Agricultural & Environmental Sciences

Description: In 1980 the Nobel Prize winning UC Berkeley physicist Luis Alvarez, his geologist son Walter Alvarez, and two nuclear chemist colleagues published the paper titled “Extraterrestrial cause for the Cretaceious-Tertiary extinction” (1980 Science 208, 1095) article in which they proposed that an asteroid that struck Earth approximately 64 million years ago was responsible for the extinction of the dinosaurs. Commonly known as the ‘asteroid impact theory’, this idea rapidly gained support among paleontologists and has become part of the accepted wisdom regarding the demise of the dinosaurs. For example, TV programs based on the expert advice of prominent paleontologists depict dinosaurs such as Tyronnosauraus rex and Brachiosaurs either being enveloped in the fireball created by the direct impact of the asteroid or slowly dying due to exposure to nuclear winter-like conditions. Although there is little question about the juxtaposition in geological time of the dinosaur extinction and the world-wide impact of an asteroid collision, no one has provided a plausible explanation of how this extinction might have occurred from an ecological and life history perspective. The theory is effectively one of eradication—the theory purports to explain how 100% of thousands of different species of dinosaur went extinct due to the direct and indirect effects of the asteroid—from the T. rex-sized dinosaurs to small insect- and seed-eating species, from the desert- and forest-dwellers to the savannah- and marsh-inhabitants, from species inhabiting the topics as well as those in polar regions. The broad purpose of this seminar is to explore whether the asteroid impact theory can stand up to ecological scrutiny. Students will be asked to bring life history theory and principles of population ecology to bear on the question of how every species of dinosaur could have become extinct worldwide due to this singular event while, at the same time, the extinction rates of other groups ranged from negligible (e.g. frogs; salamanders; placental mammals) to substantial but far from complete (e.g.,. 20-70% extinction rates for turtles, marsupials, and ray-finned fishes). In other words, why were the dinosaurs the only broad group to experience complete demise? Or to re-frame the question and assume (as do many contemporary paleontologists) that birds are living dinosaurs, why were the progenitors of modern birds the only dinosaurian group to survive the asteroid?

Format: The goals of this seminar are for students to: (1) review critically the existing theories concerning the dinosaur extinction with particular emphasis on the asteroid impact theory; (2) explore the ecological plausibility of this explanation; (3) debate both the merits and the gaps in the asteroid impact theory and propose new explanations; and (4) develop critical thinking about science and hypothesis testing in general but ecology, evolution and paleontology in particular. The seminar will meet for two hours each week for eight weeks. The first 4 weeks will involve class readings, lectures by both the instructor and invited scholars and the last 4 weeks will be devoted to student presentations, Students will be expected to do weekly reading, participate in class discussion, write a 1200-1500 work term paper on a topic related to the extinction of the dinosaurs, and make a 20 minute oral presentation to the group on their term paper topic. Grading: Students will be graded on the quality of their participation, thinking, and arguments during in-class discussion and debates (40%), on the quality of their term paper (40%) and their oral presentation (20%).

About the Instructor: Professor Carey is a professor in the Department of Entomology with research interests in the demography and ecology of aging. He is the Principal Investigator for the NIH-funded project “Oldest Old Mortality in the Mediterranean fruit fly” which is concerned with the use of medfly as a model to address questions about life span limits, gender differences in longevity, and mortality patterns at extreme ages.