Ecohydrology and paleoenvironment of the Cretaceous (Albian) Cloverly Formation: insights from multi-taxon oxygen isotope analysis of vertebrate phosphates

The Cloverly Formation of Montana and Wyoming preserves abundant nonmarine vertebrate fossils from the mid-Cretaceous, yet its paleoenvironment and faunal niche structure remain poorly understood. We analyzed δ18Οphosphate in over 100 fossil individuals from multiple vertebrate taxa collected from a...

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Main Authors: M. L. Allen, M. B. Suarez, T. L. Adams, C. A. Suarez
Format: Article
Language:English
Published: Frontiers Media S.A. 2025-05-01
Series:Frontiers in Earth Science
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Online Access:https://www.frontiersin.org/articles/10.3389/feart.2025.1497416/full
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author M. L. Allen
M. B. Suarez
T. L. Adams
C. A. Suarez
author_facet M. L. Allen
M. B. Suarez
T. L. Adams
C. A. Suarez
author_sort M. L. Allen
collection DOAJ
description The Cloverly Formation of Montana and Wyoming preserves abundant nonmarine vertebrate fossils from the mid-Cretaceous, yet its paleoenvironment and faunal niche structure remain poorly understood. We analyzed δ18Οphosphate in over 100 fossil individuals from multiple vertebrate taxa collected from a single microfossil bonebed in Carbon County, Montana.To infer habitat preferences and water-use strategies, we compared δ18Οphosphate values within and across taxa. We reconstructed δ18Osurface_water from semi-aquatic reptile values using regressions calibrated with data from modern environments and extant taxa. Using a multi-taxon framework, we estimated warm-season water temperatures from δ18Osurface_water and δ18Οphosphate of lepisosteid (gar) scales, then converted these to air temperatures using a modern climate transfer function. δ18Οphosphate values ranged from 9.5‰ to 23.2‰ (VSMOW) and varied across taxa. Aquatic and semi-aquatic groups exhibited lower values than dinosaurian taxa. Our reconstructed mean δ18Osurface_water was −7.9‰ (95% CI: −10.1 to 5.5‰), yielding a warm-season water temperature of 26°C and an air temperature of 24°C. Intertaxon differences reflect niche partitioning and suggest primary isotopic signals are preserved. Unexpectedly high values in Bernissartiid-like neosuchian teeth may indicate greater ecohydrological diversity than previously recognized. Our δ18Osurface_water estimate aligns with other Aptian-Albian proxies but exceeds model-based predictions, likely due to outdated assumptions underlying the model. The MAWSAT estimate falls within the upper range of model-data assimilation outputs. These results provide new context for ecological structure in the Cloverly fauna and offer the first quantitative temperature estimate for the Formation, helping to define baseline conditions between the Aptian-Albian Cold Snap and the Cretaceous Thermal Maximum.
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spelling doaj-art-a11ceeccdb0f490a81b8dd54f7aa50d62025-08-20T03:52:56ZengFrontiers Media S.A.Frontiers in Earth Science2296-64632025-05-011310.3389/feart.2025.14974161497416Ecohydrology and paleoenvironment of the Cretaceous (Albian) Cloverly Formation: insights from multi-taxon oxygen isotope analysis of vertebrate phosphatesM. L. Allen0M. B. Suarez1T. L. Adams2C. A. Suarez3Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, MI, United StatesDepartment of Geology, University of Kansas, Lawrence, KS, United StatesWitte Museum, San Antonio, TX, United StatesDepartment of Geosciences, Fayetteville, AR, United StatesThe Cloverly Formation of Montana and Wyoming preserves abundant nonmarine vertebrate fossils from the mid-Cretaceous, yet its paleoenvironment and faunal niche structure remain poorly understood. We analyzed δ18Οphosphate in over 100 fossil individuals from multiple vertebrate taxa collected from a single microfossil bonebed in Carbon County, Montana.To infer habitat preferences and water-use strategies, we compared δ18Οphosphate values within and across taxa. We reconstructed δ18Osurface_water from semi-aquatic reptile values using regressions calibrated with data from modern environments and extant taxa. Using a multi-taxon framework, we estimated warm-season water temperatures from δ18Osurface_water and δ18Οphosphate of lepisosteid (gar) scales, then converted these to air temperatures using a modern climate transfer function. δ18Οphosphate values ranged from 9.5‰ to 23.2‰ (VSMOW) and varied across taxa. Aquatic and semi-aquatic groups exhibited lower values than dinosaurian taxa. Our reconstructed mean δ18Osurface_water was −7.9‰ (95% CI: −10.1 to 5.5‰), yielding a warm-season water temperature of 26°C and an air temperature of 24°C. Intertaxon differences reflect niche partitioning and suggest primary isotopic signals are preserved. Unexpectedly high values in Bernissartiid-like neosuchian teeth may indicate greater ecohydrological diversity than previously recognized. Our δ18Osurface_water estimate aligns with other Aptian-Albian proxies but exceeds model-based predictions, likely due to outdated assumptions underlying the model. The MAWSAT estimate falls within the upper range of model-data assimilation outputs. These results provide new context for ecological structure in the Cloverly fauna and offer the first quantitative temperature estimate for the Formation, helping to define baseline conditions between the Aptian-Albian Cold Snap and the Cretaceous Thermal Maximum.https://www.frontiersin.org/articles/10.3389/feart.2025.1497416/fullmid-CretaceousAptian-Albianterrestrial paleoclimatevertebrate paleoecologyCloverly Formationstable oxygen isotopes
spellingShingle M. L. Allen
M. B. Suarez
T. L. Adams
C. A. Suarez
Ecohydrology and paleoenvironment of the Cretaceous (Albian) Cloverly Formation: insights from multi-taxon oxygen isotope analysis of vertebrate phosphates
Frontiers in Earth Science
mid-Cretaceous
Aptian-Albian
terrestrial paleoclimate
vertebrate paleoecology
Cloverly Formation
stable oxygen isotopes
title Ecohydrology and paleoenvironment of the Cretaceous (Albian) Cloverly Formation: insights from multi-taxon oxygen isotope analysis of vertebrate phosphates
title_full Ecohydrology and paleoenvironment of the Cretaceous (Albian) Cloverly Formation: insights from multi-taxon oxygen isotope analysis of vertebrate phosphates
title_fullStr Ecohydrology and paleoenvironment of the Cretaceous (Albian) Cloverly Formation: insights from multi-taxon oxygen isotope analysis of vertebrate phosphates
title_full_unstemmed Ecohydrology and paleoenvironment of the Cretaceous (Albian) Cloverly Formation: insights from multi-taxon oxygen isotope analysis of vertebrate phosphates
title_short Ecohydrology and paleoenvironment of the Cretaceous (Albian) Cloverly Formation: insights from multi-taxon oxygen isotope analysis of vertebrate phosphates
title_sort ecohydrology and paleoenvironment of the cretaceous albian cloverly formation insights from multi taxon oxygen isotope analysis of vertebrate phosphates
topic mid-Cretaceous
Aptian-Albian
terrestrial paleoclimate
vertebrate paleoecology
Cloverly Formation
stable oxygen isotopes
url https://www.frontiersin.org/articles/10.3389/feart.2025.1497416/full
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