Insights Into Freshwater Fish Evolution Across Major Mass Extinctions

Gars are an ancient group of ray-finned fishes that can be found today within the rivers of eastern North America, with some species extending as far north as southern Ontario. These animals are specialized carnivores adapted for catching and eating other fish, and are unusual in having undergone little change over the last 100 million years. Despite their deep history and conservative morphology, we know relatively little about their evolution due to the scarcity of complete fossil. At ROM, I am describing an exceptionally well-preserved gar fossil from the Late Cretaceous of North Dakota that represents the best-preserved Mesozoic gar found to date, and will help address significant gaps in our understanding of the evolution of these animals. Using CT scanning, 3D modelling, and computational analyses, I will investigate how this fossil gar differs from living species and other known fossils. The occurrence of this specimen during the Cretaceous offers a rare chance to understand how this lineage may have changed across the end-Cretaceous mass extinction, providing new data on ecological resilience that can benefit modern gar conservation efforts.