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Examples of vertebrate fossil data used in this study. (1) Prince Creek Formation, North Slope, C1, bonebed. (2) lower Cantwell Formation, Denali National Park, C2, ceratopsian footprint. (3) Chignik Formation, Aniakchak National Monument, C3 hadrosaur footprint. in Fiorillo, McCarthy, Kobayashi & Suarez, 2022. |
Abstract
The partially correlative Alaskan dinosaur-bearing Prince Creek Formation (PCF), North Slope, lower Cantwell Formation (LCF), Denali National Park, and Chignik Formation (CF), Aniakchak National Monument, form an N–S transect that, together, provides an unparalleled opportunity to examine an ancient high-latitude terrestrial ecosystem. The PCF, 75–85° N paleolatitude, had a Mean Annual Temperature (MAT) of ~5–7 °C and a Mean Annual Precipitation (MAP) of ~1250 mm/year. The LCF, ~71° N paleolatitude, had a MAT of ~7.4 °C and MAP of ~661 mm/year. The CF, ~57° N paleolatitude, had a MAT of ~13 °C and MAP of ~1090 mm/year. The relative abundances of the large-bodied herbivorous dinosaurs, hadrosaurids and ceratopsids, vary along this transect, suggesting that these climatic differences (temperature and precipitation) played a role in the ecology of these large-bodied herbivores of the ancient north. MAP played a more direct role in their distribution than MAT, and the seasonal temperature range may have played a secondary role.
Keywords: hadrosaurs; ceratopsians; Arctic; ancient Arctic; terrestrial ecosystems; ecosystem reconstruction
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| Figure 1. Maps showing general locations of study areas. (A) Modern Alaska. (B) Polar projection of tectonic plates during the Late Cretaceous (Base map from PLATES Project, University of Texas Institute of Geophysics). The inner latitudinal ring on map represents 45° N. (C) Examples of vertebrate fossil data used in this study. (1) Prince Creek Formation, North Slope, C1, bonebed. (2) lower Cantwell Formation, Denali National Park, C2, ceratopsian footprint, Denali National Park. (3) Chignik Formation, Aniakchak National Monument, C3 hadrosaur footprint. |
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| Examples of vertebrate fossil data used in this study. (1) Prince Creek Formation, North Slope, C1, bonebed. (2) lower Cantwell Formation, Denali National Park, C2, ceratopsian footprint, Denali National Park. (3) Chignik Formation, Aniakchak National Monument, C3 hadrosaur footprint. |
Anthony R. Fiorillo, Paul J. McCarthy, Yoshitsugu Kobayashi and Marina B. Suarez. 2022. Cretaceous Dinosaurs across Alaska Show the Role of Paleoclimate in Structuring Ancient Large-Herbivore Populations. Geosciences. 12(4) (Special Issue: Terrestrial Paleoclimatology and Paleohydrology of the Cretaceous Greenhouse World); 161. DOI: 10.3390/geosciences12040161
Cover Story: The impacts of a changing climate are of major societal concern with great interest on mitigation or modeling how a future, warmer world would look. It is also broadly recognized that the impacts of a warming Earth are most profoundly expressed in the polar regions. Climate change encompasses many components. Our new study reviews the ample evidence for a flourishing ancient Arctic terrestrial ecosystem during the Late Cretaceous greenhouse mode in Earth history, an ecosystem where the local paleoclimate was a primary driver in structuring the relative abundances of large-bodied herbivores in local environments. Further, analysis suggests that mean annual precipitation (MAP) played a more direct role in determining the distribution of herbivorous dinosaurs than mean annual temperature (MAT) did.
