This project would address the Earth's most recent mass extinction ever, the K/T boundary, from the perspective of upper Cretaceous to lower Paleocene strata on James Ross and Seymour Islands, Antarctica. Its goal is to refine the magneto and chemostratigraphy for global correlations to determine the extinction's cause. While the K/T event is widely associated with a meteorite impact, there is some evidence that it may have been caused by global climate change. This field area may contain evidence that extinction in the high southern latitudes preceded that in more temperate locales, which would support a climactic origin. The broader impacts of this work include graduate education and dissemination of results through a popular science book.
Our funded research resulted in four separate field trips to the Upper Cretaceous (90 to 65 million years ago) strata in the Antarctic Peninsula. Over three years, our team of three faculty and five different graduate students was able to make significant finds. These include: The discovery of the largest ammonite fossils (a large shell most closely related to the living Chambered Nautilus) ever found in Antarctica, and a specimen, which for the first time, had its jaws fossilized in place. These were found to look like parrot beaks and we now have a sense of what these large specimens ate. We also, for the first time, identified the numerous vertebrae impressions coming from shale sharks. Both were associated with large marine reptiles from the Age of Dinosaurs, and because these are the highest southern latitude deposits with dinosaur as well as marine fossils in it, we now have a far better idea of the living conditions at that time. We also took numerous cores as well as samples for chemical and magnetic analyses. The latter gave us the best ever geographic information about where Antarctica was during the late Age of Dinosaurs, as well as providing a high resolution method of discovery the age of the rocks at less than one million years resolution. With this new way of parsing time from individual sedimentary beds, we could, for the first time, establish rates at which the great mass extinction ending the Mesozoic Era took place. Our startling finding was that this was not one mass extinction but two – we found a precursor extinction, less substantial but nevertheless significant, that occurred in the last hundred thousand years of the Cretaceous Period. We do substantiate evidence for asteroid impact at the end of the Cretaceous, with evidence in Antarctica confirming that this was a global event. But the earlier extinction had nothing to do with large body impact on the Earth: instead, it coincided with a period of volcanism that warmed the climate. This warming was directly substantiated by our samples taken for chemistry, for they contain a direct temperature measure that was teased out of these samples in the laboratory. The result is unmistakable – short term global warming, brought about by large and short term injection of carbon dioxide (a "Greenhouse" gas) into the atmosphere warmed the planet, which led to a loss of oxygen in the oceans, which then killed a significant number of bottom dwelling animals. The amounts of heating increase were on par with the predicted heating of our planet currently from human produced (coupled with the normal volcanic output, of course) greenhouse gases. The significant is that we have direct evidence that rises in global temperature of as little as 4-5 degrees (centigrade) changed a high diversity, underwater community into a lower diversity one. This should serve as a significant warning to humanity, and a significant rebuke to climate change deniers. The deep past holds the most important evidence, and we think our results are as robust as any ever made in this area. In final summary: we increased understanding of the Antarctic animal marine communities and the paleobiology of their marine inhabitants from about (in our field areas) 84 to 65 million years ago. We separately used core samples to understand the latitude at that time, as well as subdividing the strata in units of time of higher resolution than any ever made; that work allowed us to make an inventory of the animals in the oceans there at million year intervals. With this high resolution, we then discovered that a previously unrecognized mass extinction had occurred in Antarctica, one caused by short term global warming.
