Uppsala University Doctoral Thesis Defence: Unveiling New Insights into Life Before the KPg Extinction

During's research provides new insights into life just before the Cretaceous-Paleogene (KPg) extinction, one of the most dramatic events in Earth's history, which wiped out ~ 75% of species, including non-avian dinosaurs. Her work pinpoints boreal spring as the season when the catastrophic meteorite impact occurred, adding a crucial piece of knowledge to our understanding of this extinction event.

The research explores the selective nature of the extinction and its immediate aftermath as documented in the fossil record, including the diversity of the end-Cretaceous freshwater ecosystem in North Dakota. Notably, it examines paddlefishes (a group of basal ray-finned fishes that have one living member in North America) and the entirely unexpected mosasaurs (giant predatory lizards, normally viewed as wholly marine, which perished in the extinction event). By integrating geochemical and osteohistological analyses, this research sheds new light on both the timing of the impact and the ecosystems that thrived just before the extinction.

The thesis also features the development of an online AI-assisted segmentation tool for tomographic data, addressing specific challenges encountered in segmentation tasks for paleontological imaging, such as contrast variations and metallic inclusions, which often hinder traditional approaches. By offering a user-friendly interface for 2D slice-based image segmentation, ml4paleo facilitates the segmentation of complex fossil data, making advanced imaging techniques more accessible to researchers across multiple scientific disciplines. The software's open-source nature ensures that it can be further developed and applied in various fields, from palaeontology to other branches of science that rely on tomographic data. While distinct from the core themes of the thesis, this work plays a crucial role in advancing the technical tools available for fossil analysis and reflects a commitment to improving the accessibility and quality of tomographic imaging in paleontological research.

This work makes significant contributions to the fields of paleobiology and geochemistry, enhancing our understanding of how life responded to and was ultimately affected by one of Earth's most profound extinction events.

In addition to her research, Melanie is passionate about science communication and the popularization of science. She actively engages with various audiences to share her findings and promote an understanding of paleontological research.

In closing, Melanie looks forward to using her experience at the interface of research and science communication to make more discoveries and educate society about extinctions, both then and now.

For questions about the research, you can approach Per Ahlberg (per.ahlberg@ebc.uu.se) or Melanie During (melanie.during@ebc.uu.se) [please note that she has very limited availability in the days leading up to her defence]