Postdoctoral Fellowship: EAR-PF: A multiscalar examination of freshwater fish extinction and recovery across the Cretaceous/Paleogene boundary

Dr. Jacob Wilson has been awarded an EAR Postdoctoral Fellowship to conduct research and professional development activities under the mentorship of Dr. Tyler Lyson at the Denver Museum of Nature and Science and Dr.

Blair Schoene at the Princeton University. Humans have started a biodiversity crisis on the Earth that is likely to cause high extinction of many organisms in the near future. Scientists can add to our understanding of this crisis by studying the past.

In Earth history there have been at least five major events where extinction was greatly increased. These are called mass extinctions. The most recent mass extinction was ~66 million years ago.

This event is known as the Cretaceous/Paleogene (K/Pg) event. From research on the K/Pg, we know that it caused the extinction of the dinosaurs (except birds) and led to the rise of many groups of mammals that are around us today. Scientists have also studied many other organisms from the time of the K/Pg.

One gap in our understanding is freshwater fish, which today represent one quarter of living animals with a backbone, with over 18,000 species. Despite how many of them there are today, what happened to freshwater fish during the K/Pg extinction remains a mystery. PI Wilson’s research will include field work to find and study fish fossils from sites in the western United States.

One of these is a unique site in central Colorado that has a layer of rock from the event that killed the dinosaurs. PI Wilson will also study chemicals in rocks to test whether a famous site in North Dakota is from the ‘day the dinosaurs died.’ Together, this work will use full fossil skeletons down to the tiniest pieces of bone to study what happened to freshwater fish when the dinosaurs went extinct.

The results of this research can help humanity to face the conservation challenges of the current crisis. As part of these studies, PI Wilson will work with community volunteers and local high school students in the Teen Science Scholars program at the Denver Museum and undergraduate students at Princeton University. Through museum exhibits, interactive video conferences, and in-person discussions, PI Wilson will share his research with the public, including students and museum patrons of all ages.

This work will consist of four projects chosen to both contribute to our understanding of freshwater fish diversity dynamics around the K/Pg and also to build and curate valuable datasets of use to the wider scientific community. The first project will expand collections of microfossils in critical stratigraphic sequences from the unique West Bijou study area of Colorado to provide high-resolution information on post-K/Pg recovery in the Denver Basin.

PI Wilson will then use CA-ID-TIMS U-Pb geochronology to date volcanic ash horizons from West Bijou and build a timescale of recovery that will serve as a temporal framework for scientific study of the K/Pg. Description of several articulated specimens from near-K/Pg sediments across sites in the western United States will provide insight on alpha diversity in freshwater ecosystems of the time and will contribute to our understanding of lineages that perished from or survived the K/Pg event.

Finally, a preliminary analysis on the presence and age of zircons from the Tanis locality will provide a much-needed independent test of the working hypothesis that the site was deposited by seiche activity in the Western Interior Seaway in the immediate aftermath of the K/Pg impact. Together, PI Wilson’s work will integrate information from different analytical disciplines to expand our understanding of the K/Pg event and the ongoing ‘sixth mass extinction’.

PI Wilson will mentor high school students interested in STEM careers through the Teen Science Scholars program at the Denver Museum. The ongoing ‘After the Asteroid’ exhibit at the museum will be an outlet to share his research, and he will further communicate with students of grades 4–12 around the USA as part of the Scientists in Action program.

At Princeton, PI Wilson will work with local K12 science teachers to facilitate communication of cutting-edge research to students and will mentor undergraduate researchers in the Department of Geosciences.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.