Late Cretaceous Fishes of Uzbekistan: Dispersal and Climate-Driven Ecological Change скачать в хорошем качестве

Late Cretaceous Fishes of Uzbekistan: Dispersal and Climate-Driven Ecological Change

Presented by Dr. Donald Brinkman, Royal Tyrrell Museum of Palaeontology, February 26, 2026. The Bissekty Formation (Late Cretaceous, Turonian, Uzbekistan) preserves an assemblage of fossil boney fishes that is remarkably similar to that from North America. Eight of the taxa that first appear in the Bissekty Formation being indistinguishable from, or closely related to taxa present in the North American portion of Laurasia. This similarity indicates there were strong biogeographic connections between these areas. However, only two of the shared taxa are known to occur in North America during the Turonian. The remaining taxa first occur in a stepwise fashion during the Late Cretaceous. Comparison of the Bissekty Formation assemblage with the earlier Cenomanian assemblages of Asia and North America shows that a major faunal change occurred at this time. In both places, two taxa, the lepidotid Scheenstia (Lepidotidae) and a pycnodont, either become very rare or disappear completely. Also, new taxa appear. One of these, the characiform Primuluchara sp., is a member of a typically southern hemisphere group, so its presence in Laurasia has been assumed to be the result of an intercontinental dispersal event. These faunal changes coincide with a period of high global temperature, called the Turonian thermal maximum, suggesting that they are a result of this climatic event. The results of this study underscore the importance of vertebrate microfossils in reconstructing Cretaceous palaeoecology and highlight the role of climate change in driving evolutionary patterns in freshwater ecosystems. Future research integrating additional fossil data and palaeoclimate modeling will further refine our understanding of the impact of the Turonian thermal maximum on the composition and distribution of palaeocommunities of the Late Cretaceous. Additional reference: Slide 28: The image of Clupea harengus courtesy of Norman Weaver, from the book “Fishes of the World” by Migdalski and Fichter.