2 Interdisciplinary Paleontology: New approaches to solving complex paleontological problems (Part I)

Paleontology is increasingly drawing upon insight from other disciplines to solve complex problems and generate more accurate reconstructions of past life. This session will illustrate novel interdisciplinary research and provide tools to develop such approaches.

Monday, 18 May 2026
8:00 AM - 12:00 PM
Alvarado F

Evidence of Climate-Associated Size Reduction in High-Elevation Small Mammals in northern Utah

Paper number: 2-3
Program: Technical Sessions
Time: 9:00 AM – 9:20 AM

Authors

Abstract

Climate change is altering temperature regimes at a global scale, driving widespread ecological responses across taxa and biomes. One example of these effects is Bergmann’s Rule, a well-documented ecological pattern in which mammalian body size exhibits an inverse relationship with temperature, allowing them to optimally mitigate heat stress. The mass of an animal directly impacts an ecosystem’s energy flow, nutrient cycling, and extinction rates. Previous studies have investigated this trend by examining the national database of North American Mammals, finding that small mammal body mass consistently shrinks in response to warmer ambient temperatures. Because climatic variation directly shapes organismal physiology and morphology, these broad-scale patterns raise an important question: do temperature–body size relationships predicted by Bergmann’s Rule persist at local scales, particularly within sensitive high-elevation ecosystems that may be especially vulnerable to rapid environmental change? This study investigates the impact of increasing global temperatures on the body size of small mammals over time. We compared pre-Industrial fossil craniodental samples of small mammals from both Thundershower and Boomerang caves in Utah’s Bear River Range (Uinta-Wasatch-Cache National Forest) to corresponding modern specimens collected from Utah’s Cache County, housed in the Natural History Museum of Utah. Following established methodologies, six linear morphometric variables were measured. Missing measurements due to incomplete elements were imputed using random forest modeling, after which statistical comparisons between paleontological and modern samples were conducted using t-tests to detect significant differences in size for each measurement. Five of the eight studied taxa exhibit statistically significant reductions in size in at least one measurement, consistent with Bergmann’s Rule. The most pronounced changes were observed in bushy-tailed woodrats (Neotoma cinerea), suggesting that this species may be particularly responsive to thermal stress. This heightened sensitivity might stem from their physiological adaptation to cold, high-elevation environments. For instance, rising temperatures in the region may be imposing metabolic strain and restricting foraging time. As a result, these energetic constraints may alter bushy-tailed woodrat growth allocation during development, ultimately influencing overall body size and, correspondingly, tooth dimensions in response to sustained warming. These findings underscore the broader implications of cave fossil assemblages for investigating climate-driven body size change in small mammals. 

Geological Society of America Abstracts with Programs. Vol. 58, No. 4

doi: 10.1130/abs/2026RM-410672

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