ORIGINAL RESEARCH article
Front. Earth Sci.
Sec. Paleontology
Volume 13 - 2025 | doi: 10.3389/feart.2025.1497416
Ecohydrology and paleoenvironment of the Cretaceous (Albian) Cloverly Formation: Insights from multi-taxon oxygen isotope analysis of vertebrate phosphates
Provisionally accepted
- 1University of Michigan, Ann Arbor, Michigan, United States
- 2University of Kansas, Lawrence, Kansas, United States
- 3Witte Museum, San Antonio, United States
- 4University of Arkansas, Fayetteville, North Carolina, United States
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The Cloverly Formation of Montana and Wyoming is one of the few units in the North American Western Interior that preserves abundant nonmarine vertebrate fossils from the mid-Cretaceous, yet its paleoenvironment and the niche structure of its vertebrate fauna remain poorly understood. Stable oxygen isotopes from vertebrate phosphate offer a means to address both. We analyzed d 18 Ophosphate in over 100 fossil individuals from multiple taxa collected from a single microfossil bonebed in Carbon County, Montana. By comparing d 18 Ophosphate distributions within and across taxa, we inferred habitat preferences and water-use strategies. For most groups, oxygen isotope values aligned with expected ecological habits (e.g., semi-aquatic vs. terrestrial). However, Bernissartiid-like neosuchian teeth yielded values inconsistent with prior ecological interpretations. We reconstructed δ¹⁸Osurface_water from semi-aquatic reptile d 18 Ophosphate using the regressions of Barrick et al. (1999) and Amiot et al. (2007), producing a mean estimate of -7.9‰ VSMOW (95% CI: -10.1, -5.5‰). This value aligns with other proxy-based estimates from the Aptian-Albian Western Interior but is notably higher than latitude-adjusted model predictions. We discuss potential explanations for this proxy-model mismatch. Using a multi-taxon approach following Fricke and Wing ( 2004), we estimate a mean annual warm-season water temperature (MAWSWT) of 26 °C (95% CI: 8, 43 °C) based on d 18 Osurface_water and d 18 Ophosphate from lepisosteid enameloid. This corresponds to a mean annual warm-season air temperature (MAWSAT) of 24 °C (95% CI: 9, 41 °C) using a transform function derived from modern climate data. Our MAWSAT estimate is consistent with other proxy-based reconstructions and falls within the upper range of model-data assimilation outputs for this paleolatitude. This is among the first quantitative terrestrial temperature estimates for the Albian of North America and helps to establish baseline conditions following the Aptian Albian Cold Snap and prior to the Cretaceous Thermal Maximum.
Keywords: mid-Cretaceous1, Cloverly2, oxygen3, isotopes4, paleoclimate5. (Min
Received: 04 Oct 2024; Accepted: 15 Apr 2025.
Copyright: © 2025 Allen, Suarez, Adams and Suarez. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Marina Suarez, University of Kansas, Lawrence, 66045, Kansas, United States
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