Organoid models of human and mouse ductal pancreatic cancer.

Pancreatic cancer is one of the most lethal malignancies due to its late diagnosis and limited response to treatment. Tractable methods to identify and interrogate pathways involved in pancreatic tumorigenesis are urgently needed. We established organoid models from normal and neoplastic murine and human pancreas tissues. Pancreatic organoids can be rapidly generated from resected tumors and biopsies, survive cryopreservation, and exhibit ductal- and disease-stage-specific characteristics. Orthotopically transplanted neoplastic organoids recapitulate the full spectrum of tumor development by forming early-grade neoplasms that progress to locally invasive and metastatic carcinomas. Due to their ability to be genetically manipulated, organoids are a platform to probe genetic cooperation. Comprehensive transcriptional and proteomic analyses of murine pancreatic organoids revealed genes and pathways altered during disease progression. The confirmation of many of these protein changes in human tissues demonstrates that organoids are a facile model system to discover characteristics of this deadly malignancy.

Food and Nutrition Insecurity: Experiences That Differ for Some and Independently Predict Diet-Related Disease, Los Angeles County, 2022.

BACKGROUND: National surveillance shows that food insecurity affects ∼1 in 10 Americans each year. Recently, experts have advocated for surveillance of nutrition insecurity alongside food insecurity. Nutrition security refers to the nutritional adequacy of accessible food and factors that impact one's ability to meet food preferences. OBJECTIVES: This study presents representative estimates of food insecurity and nutrition insecurity for Los Angeles County, CA, United States; compares predictors of these constructs; and examines whether they independently predict diet-related health outcomes. METHODS: In December 2022, a representative sample of Los Angeles County adults participating in the Understanding America Study (N = 1071) was surveyed about household food insecurity and nutrition insecurity over the past 12 months. Data were analyzed in 2023. RESULTS: Reported rates were similar for food insecurity (24%) and nutrition insecurity (25%), but the overlap of these subgroups was less than 60%. Logistic regression models indicated that non-Hispanic Asian individuals had higher odds of nutrition insecurity but not food insecurity. Moreover, nutrition insecurity was a stronger predictor of diabetes compared with food insecurity, and both constructs independently predicted poor mental health. CONCLUSIONS: Food and nutrition insecurity affect somewhat different populations. Both constructs are valuable predictors of diet-related health outcomes. Monitoring nutrition insecurity in addition to food insecurity can provide new information about populations with barriers to healthy diets.

Smartphone GPS-Based Exposure to Greenspace and Walkability and Accelerometer-Assessed Physical Activity During Pregnancy and Early Postpartum-Evidence from the MADRES Cohort.

A growing number of studies have associated walkability and greenspace exposure with greater physical activity (PA) in women during pregnancy. However, most studies have focused on examining women's residential environments and neglected exposure in locations outside the home neighborhood. Using 350 person-days (N = 55 participants) of smartphone global positioning system (GPS) location and accelerometer data collected during the first and third trimesters and 4-6 months postpartum from 55 Hispanic pregnant women from the Maternal and Developmental Risks from Environmental and Social Stressors (MADRES) study, we examined the day-level effect of women's exposure to walkability and greenspace on their PA outcomes during pregnancy and in the early postpartum period. Moderate-to-vigorous physical activity [MVPA] minutes per day was assessed using accelerometers. Walkability and greenspace were measured using geographic information systems (GIS) within women's daily activity spaces (i.e., places visited and routes taken) recorded using a smartphone GPS and weighted by time spent. We used a generalized linear mixed-effects model to estimate the effects of daily GPS-derived environmental exposures on day-level MVPA minutes. Results showed that women engaged in 23% more MVPA minutes on days when they had some versus no exposure to parks and open spaces in activity spaces (b = 1.23; 95%CI: 1.02-1.48). In addition, protective effects of daily greenspace and walkability exposure on MVPA were stronger in the first and third trimesters, among first-time mothers, and among women who had high pre-pregnancy body mass index (BMI) and lived in least-safe neighborhoods. Our results suggest that daily greenspace and walkability exposure are important for women's PA and associated health outcomes during pregnancy and early postpartum.

Socio-ecological factors linked with changes in adults' dietary intake in Los Angeles County during the peak of the coronavirus 2019 pandemic.

OBJECTIVE: Comprehensive studies examining longitudinal predictors of dietary change during the coronavirus disease 2019 pandemic are lacking. Based on an ecological framework, this study used longitudinal data to test if individual, social and environmental factors predicted change in dietary intake during the peak of the coronavirus 2019 pandemic in Los Angeles County and examined interactions among the multilevel predictors. DESIGN: We analysed two survey waves (e.g. baseline and follow-up) of the Understanding America Study, administered online to the same participants 3 months apart. The surveys assessed dietary intake and individual, social, and neighbourhood factors potentially associated with diet. Lagged multilevel regression models were used to predict change from baseline to follow-up in daily servings of fruits, vegetables and sugar-sweetened beverages. SETTING: Data were collected in October 2020 and January 2021, during the peak of the coronavirus disease 2019 pandemic in Los Angeles County. PARTICIPANTS: 903 adults representative of Los Angeles County households. RESULTS: Individuals who had depression and less education or who identified as non-Hispanic Black or Hispanic reported unhealthy dietary changes over the study period. Individuals with smaller social networks, especially low-income individuals with smaller networks, also reported unhealthy dietary changes. After accounting for individual and social factors, neighbourhood factors were generally not associated with dietary change. CONCLUSIONS: Given poor diets are a leading cause of death in the USA, addressing ecological risk factors that put some segments of the community at risk for unhealthy dietary changes during a crisis should be a priority for health interventions and policy.

Geospatial techniques for monitoring and mitigating climate change and its effects on human health.

This article begins by briefly examining the multitude of ways in which climate and climate change affect human health and wellbeing. It then proceeds to present a quick overview of how geospatial data, methods and tools are playing key roles in the measurement, analysis and modelling of climate change and its effects on human health. Geospatial techniques are proving indispensable for making more accurate assessments and estimates, predicting future trends more reliably, and devising more optimised climate change adaptation and mitigation plans.

Ecological risk and protective factors for food insufficiency in Los Angeles County during the COVID-19 pandemic.

OBJECTIVE: The COVID-19 pandemic increased food insufficiency: a severe form of food insecurity. Drawing on an ecological framework, we aimed to understand factors that contributed to changes in food insufficiency from April to December 2020, in a large urban population hard hit by the pandemic. DESIGN: We conducted internet surveys every 2 weeks in April-December 2020, including a subset of items from the Food Insecurity Experience Scale. Longitudinal analysis identified predictors of food insufficiency, using fixed effects models. SETTING: Los Angeles County, which has a diverse population of 10 million residents. PARTICIPANTS: A representative sample of 1535 adults in Los Angeles County who are participants in the Understanding Coronavirus in America tracking survey. RESULTS: Rates of food insufficiency spiked in the first year of the pandemic, especially among participants living in poverty, in middle adulthood and with larger households. Government food assistance from the Supplemental Nutrition Assistance Program was significantly associated with reduced food insufficiency over time, while other forms of assistance such as help from family and friends or stimulus funds were not. CONCLUSIONS: The findings highlight that during a crisis, there is value in rapidly monitoring food insufficiency and investing in government food benefits.

American Indian and Alaska Native Accessibility to Comprehensive Cleft Lip and Palate Treatment.

American Indians and Alaska Natives (AI/AN) have the highest incidence of cleft lip and palate (orofacial clefts [OFCs]) when compared to other ethnic groups. We aim to determine the AI/AN populations' proximity and accessibility to American Cleft Palate-Craniofacial Association accredited centers (ACPA centers) for treatment of OFCs. Our hypothesis is an unacceptable proportion of the AI/AN population lacks reasonable accessibility to ACPA centers and comprehensive craniofacial care.A cross-sectional study of ACPA centers and AI/AN populations were analyzed for possible disparities.ACPA centers were mapped using Geographic Information Systems (GIS) and compared with 2018 census population data and 2017 Tribal Census Tract data to visually display possible disparities. Total annual potential pediatric cleft care need for selected high-density AI/AN populated lands were estimated.GIS mapping demonstrates geographical isolation of AI/AN populations from ACPA centers. Two states with high AI/AN populated lands (ND, WY) have no ACPA centers. 47.1% of ACPA centers in high AI/AN populated lands have no craniofacial trained surgeons versus 78.9% craniofacial staffed ACPA centers nationally. The potential unmet cleft and craniofacial care need in selected high-density AI/AN populated lands is 1042 children.AI/AN populations are likely underserved by ACPA centers and by craniofacial fellowship-trained staffed centers. Not addressing OFCs with comprehensive care can lead to worsened outcomes and further marginalization of these children. With future studies, we will be capable of making data-driven, informed decisions to more effectively ensure AI/AN access to comprehensive cleft and craniofacial care.

Alcohol use trajectories among U.S. adults during the first 42 weeks of the COVID-19 pandemic.

BACKGROUND: This study characterized the prevalence, drinking patterns, and sociodemographic characteristics of U.S. adult subpopulations with distinct drinking trajectories during the COVID-19 pandemic's first 42 weeks. METHODS: Adult respondents (n = 8130) in a nationally representative prospective longitudinal study completed 21 biweekly web surveys (March 2020 to January 2021). Past-week alcohol drinking frequency (drinking days [range: 0 to 7]) and intensity (binge drinking on usual past-week drinking day [yes/no]) were assessed at each timepoint. Growth mixture models identified multiple subpopulations with homogenous drinking trajectories based on mean drinking days or binge drinking proportional probabilities across time. RESULTS: Four drinking frequency trajectories were identified: Minimal/stable (72.8% [95% CI = 71.8 to 73.8]) with <1 mean past-week drinking days throughout; Moderate/late decreasing (6.7% [95% CI = 6.2 to 7.3) with 3.13 mean March drinking days and reductions during summer, reaching 2.12 days by January 2021; Moderate/early increasing (12.9% [95% CI = 12.2 to 13.6) with 2.13 mean March drinking days that increased in April and then plateaued, ending with 3.20 mean days in January 2021; and Near daily/early increasing (7.6% [95% CI = 7.0 to 8.2]) with 5.58 mean March drinking days that continued increasing without returning to baseline. Four drinking intensity trajectories were identified: Minimal/stable (85.8% [95% CI = 85.0% to 86.5%]) with <0.01 binge drinking probabilities throughout; Low-to-moderate/fluctuating (7.4% [95% CI = 6.8% to 8%]) with varying binge probabilities across timepoints (range:0.12 to 0.26); Moderate/mid increasing (4.2% [95% CI = 3.7% to 4.6%]) with 0.39 April binge drinking probability rising to 0.65 during August-September without returning to baseline; High/early increasing trajectory (2.7% [95% CI = 2.3% to 3%]) with 0.84 binge drinking probability rising to 0.96 by June without returning to baseline. Males, Whites, middle-aged/older adults, college degree recipients, those consistently working, and those above the poverty limit were overrepresented in various increasing (vs. minimal/stable) frequency trajectories. Males, Whites, nonmarried, those without college degree, 18 to 39-year-olds, and middle aged were overrepresented in increasing (vs. minimal/stable) intensity trajectories. CONCLUSIONS: Several distinct U.S. adult sociodemographic subpopulations appear to have acquired new drinking patterns during the pandemic's first 42 weeks. Frequent alcohol use assessment in the COVID-19 era could improve personalized medicine and population health efforts to reduce drinking.

The impact of GPS-derived activity spaces on personal PM2.5 exposures in the MADRES cohort.

BACKGROUND: In-utero exposure to particulate matter with aerodynamic diameter less than 2.5 µm (PM2.5) is associated with low birth weight and health risks later in life. Pregnant women are mobile and locations they spend time in contribute to their personal PM2.5 exposures. Therefore, it is important to understand how mobility and exposures encountered within activity spaces contribute to personal PM2.5 exposures during pregnancy. METHODS: We collected 48-h integrated personal PM2.5 samples and continuous geolocation (GPS) data for 213 predominantly Hispanic/Latina pregnant women in their 3rd trimester in Los Angeles, CA. We also collected questionnaires and modeled outdoor air pollution and meteorology in their residential neighborhood. We calculated three GPS-derived activity space measures of exposure to road networks, greenness (NDVI), parks, traffic volume, walkability, and outdoor PM2.5 and temperature. We used bivariate analyses to screen variables (GPS-extracted exposures in activity spaces, individual characteristics, and residential neighborhood exposures) based on their relationship with personal, 48-h integrated PM2.5 concentrations. We then built a generalized linear model to explain the variability in personal PM2.5 exposure and identify key contributing factors. RESULTS: Indoor PM2.5 sources, parity, and home ventilation were significantly associated with personal exposure. Activity-space based exposure to roads was associated with significantly higher personal PM2.5 exposure, while greenness was associated with lower personal PM2.5 exposure (ß = -3.09 µg/m3 per SD increase in NDVI, p-value = 0.018). The contribution of outdoor PM2.5 to personal exposure was positive but relatively lower (ß = 2.05 µg/m3 per SD increase, p-value = 0.016) than exposures in activity spaces and the indoor environment. The final model explained 34% of the variability in personal PM2.5 concentrations. CONCLUSIONS: Our findings highlight the importance of activity spaces and the indoor environment on personal PM2.5 exposures of pregnant women living in Los Angeles, CA. This work also showcases the multiple, complex factors that contribute to total personal PM2.5 exposure.

Estimation of the relative contributions of forest areal expansion and growth to China's forest stand biomass carbon sequestration from 1977 to 2018.

As a prominent part of global and regional terrestrial carbon (C) pools, increases in forest biomass C sinks can be attributed to either forest areal expansion (FAE) or increased biomass C density (IBCD). Accurate estimates of the relative contributions of FAE and IBCD to forest C sequestration can improve our understanding of forest C cycling processes and will help to formulate rational afforestation policies to cope with global warming. In this study, the Continuous Biomass Expansion Factor (CBEF) model and Forest Identity concept were used to map the spatiotemporal variation of the relative contribution of FAE and IBCD to the C sequestration of forest (natural and planted forests) in China and seven regions during the past 40 years. Our results suggest that: (1) total forest biomass C density and stocks of forest increased from 35.41 Mg C ha-1 and 4128.50 Tg C to 43.95 Mg C ha-1 and 7906.23 Tg C in China from 1977 to 2018, respectively; (2) for all forests, the IBCD has been a smaller contributor to C sinks than FAE in China from 1977 to 2018 (33.27 vs. 66.73%); (3) the contribution of FAE to C sinks is greater than that of IBCD in planted forests (63.99 vs. 36.01%), while in natural forests, IBCD has a larger contribution than FAE (57.82 vs. 42.18%) from 1977 to 2018 and the relative contribution of FAE has exceeded IBCD in the last decade; and (4) these patterns varied at the regional level such that the relative contribution of FAE increased for planted forests in most regions but for natural forests, IBCD gradually reached saturation and C stocks declined in northern regions in the last decade. The results from this study suggest that total biomass C sinks will keep increasing because of the increased forest area contributed by afforestation and the relatively young trees in planted forests. This study facilitates a more comprehensive assessment of forest C budgets and improves our understanding of ecological mechanisms of forest biomass carbon stock and dynamics.

Detergent-Free Simultaneous Sample Preparation Method for Proteomics and Metabolomics.

The integration of omics techniques has seen a step change in our understanding of biological systems. However, multiomics has been impaired by mutually exclusive omic separation methods and the destructive nature of the techniques when sample is limited. We describe Simultaneous Trapping (SiTrap), a simple and effective detergent-free method that facilitates direct measurement of the proteome and metabolome in the same sample extract. This "single-pot" multiomics processing is particularly beneficial in cases when sample amounts are limited or are heterogeneous, for example, tissue biopsies. We demonstrate the value of the SiTrap methodology as an essential multiomics tool in a proof-of-principle integrated study of renal cancer tissue biopsy samples. We believe SiTrap has the potential to become an indispensable tool in translational medical research.

HYPERsol: High-Quality Data from Archival FFPE Tissue for Clinical Proteomics.

Massive formalin-fixed, paraffin-embedded (FFPE) tissue archives exist worldwide, representing an invaluable resource for clinical proteomics research. However, current protocols for FFPE proteomics lack standardization, efficiency, reproducibility, and scalability. Here we present high-yield protein extraction and recovery by direct solubilization (HYPERsol), an optimized workflow using ultrasonication and S-Trap sample processing that enables proteome coverage and quantification from FFPE samples comparable to that achieved from flash-frozen tissue (average R = 0.936). When applied to archival samples, HYPERsol resulted in high-quality data from FFPE specimens in storage for up to 17 years, and may enable the discovery of new immunohistochemical markers.

Tryp-N: A Thermostable Protease for the Production of N-terminal Argininyl and Lysinyl Peptides.

Bottom-up proteomics is a mainstay in protein identification and analysis. These studies typically employ proteolytic treatment of biological samples to generate suitably sized peptides for tandem mass spectrometric (MS) analysis. In MS, fragmentation of peptides is largely driven by charge localization. Consequently, peptides with basic centers exclusively on their N-termini produce mainly b-ions. Thus, it was long ago realized that proteases that yield such peptides would be valuable proteomic tools for achieving simplified peptide fragmentation patterns and peptide assignment. Work by several groups has identified such proteases, however, structural analysis of these suggested that enzymatic optimization was possible. We therefore endeavored to find enzymes that could provide enhanced activity and versatility while maintaining specificity. Using these previously described proteases as informatic search templates, we discovered and then characterized a thermophilic metalloprotease with N-terminal specificity for arginine and lysine. This enzyme, dubbed Tryp-N, affords many advantages including improved thermostability, solvent and detergent tolerance, and rapid digestion time.

Depth-dependent soil organic carbon dynamics of croplands across the Chengdu Plain of China from the 1980s to the 2010s.

Agricultural soils have tremendous potential to sequester soil organic carbon (SOC) and mitigate global climate change. However, agricultural land use has a profound impact on SOC dynamics, and few studies have explored how agricultural land use combined with soil conditions affect SOC changes throughout the soil profile. Based on a paired soil resampling campaign in the 1980s and 2010s, this study investigated the SOC changes of the soil profile caused by agricultural land use and the correlations with parent material and topography across the Chengdu Plain of China. The results showed that the SOC content increased by 3.78 g C/kg in the topsoil (0-20 cm), but decreased in the 20-40 cm and 40-60 cm soil layers by 0.90 and 1.26 g C/kg respectively. SOC increases in topsoil were observed for all types of agricultural land. Afforestation on former agricultural land also caused SOC decreases in the 20-60 cm soil layers, while SOC decreases only occurred in the 40-60 cm soil layer for agricultural land using a traditional crop rotation (i.e. traditional rice-wheat/rapeseed rotation) and with rice-vegetable rotations converted from the traditional rotations. For each agricultural land use, SOC decreases in deep soils only occurred in high relief areas and in soils formed from Q4 (Quaternary Holocene) grey-brown alluvium and Q4 grey alluvium that had a relatively low soil bulk density and clay content. The results indicated that SOC change caused by agricultural land use was depth dependent and that the effects of agricultural land use on soil profile SOC dynamics varied with soil characteristics and topography. Subsoil SOC decreases were more likely to occur in high relief areas and in soils with low soil bulk density and low clay content.

Mapping fires and American Red Cross aid using demographic indicators of vulnerability.

Social vulnerability indicators can assist with informing disaster relief preparation. Certain demographic segments of a population may suffer disproportionately during disaster events, and a geographical understanding of them can help to determine where to place strategically logistical assets and to target disaster-awareness outreach endeavours. Records of house fire events and American Red Cross aid provision over a five-year period were mapped for the County of Los Angeles, California, United States, to examine the congruence between actual events and expectations of risk based on vulnerability theory. The geographical context provided by the data was compared with spatially-explicit indicators of vulnerability, such as age, race, and wealth. Fire events were found to occur more frequently in more vulnerable areas, and Red Cross aid was found to have an even stronger relationship to those places. The findings suggest that these indicators speak beyond vulnerability and relate to patterns of fire risk.

Guanylate-Binding Protein-1 protects ovarian cancer cell lines but not breast cancer cell lines from killing by paclitaxel.

Forced expression of the cytokine-induced large GTPase, human Guanylate-Binding Protein-1 (hGBP-1), in ovarian cancer cell lines increases resistance to paclitaxel. Elevated hGBP-1 RNA in ovarian tumors correlates with shorter recurrence-free survival. In contract, hGBP-1 is part of a gene signature predicting improved prognosis in all subtypes of breast cancers. hGBP-1 does not confer paclitaxel resistance on MCF-7 and TMX2-28 breast cancer cells. Expression of the isotype of the hGBP-1-interacting protein, PIM1, which may contribute to paclitaxel resistance when associated with hGBP-1, is different in breast and ovarian cancer cell lines. Breast cancer cell lines express the 44 kDa isoform of PIM-1, and ovarian cancer cell lines express the 33 kDa isoform.

Modelling of XCO2 Surfaces Based on Flight Tests of TanSat Instruments.

The TanSat carbon satellite is to be launched at the end of 2016. In order to verify the performance of its instruments, a flight test of TanSat instruments was conducted in Jilin Province in September, 2015. The flight test area covered a total area of about 11,000 km² and the underlying surface cover included several lakes, forest land, grassland, wetland, farmland, a thermal power plant and numerous cities and villages. We modeled the column-average dry-air mole fraction of atmospheric carbon dioxide (XCO2) surface based on flight test data which measured the near- and short-wave infrared (NIR) reflected solar radiation in the absorption bands at around 760 and 1610 nm. However, it is difficult to directly analyze the spatial distribution of XCO2 in the flight area using the limited flight test data and the approximate surface of XCO2, which was obtained by regression modeling, which is not very accurate either. We therefore used the high accuracy surface modeling (HASM) platform to fill the gaps where there is no information on XCO2 in the flight test area, which takes the approximate surface of XCO2 as its driving field and the XCO2 observations retrieved from the flight test as its optimum control constraints. High accuracy surfaces of XCO2 were constructed with HASM based on the flight's observations. The results showed that the mean XCO2 in the flight test area is about 400 ppm and that XCO2 over urban areas is much higher than in other places. Compared with OCO-2's XCO2, the mean difference is 0.7 ppm and the standard deviation is 0.95 ppm. Therefore, the modelling of the XCO2 surface based on the flight test of the TanSat instruments fell within an expected and acceptable range.

Linking pesticides and human health: a geographic information system (GIS) and Landsat remote sensing method to estimate agricultural pesticide exposure.

Accurate pesticide exposure estimation is integral to epidemiologic studies elucidating the role of pesticides in human health. Humans can be exposed to pesticides via residential proximity to agricultural pesticide applications (drift). We present an improved geographic information system (GIS) and remote sensing method, the Landsat method, to estimate agricultural pesticide exposure through matching pesticide applications to crops classified from temporally concurrent Landsat satellite remote sensing images in California. The image classification method utilizes Normalized Difference Vegetation Index (NDVI) values in a combined maximum likelihood classification and per-field (using segments) approach. Pesticide exposure is estimated according to pesticide-treated crop fields intersecting 500 m buffers around geocoded locations (e.g., residences) in a GIS. Study results demonstrate that the Landsat method can improve GIS-based pesticide exposure estimation by matching more pesticide applications to crops (especially temporary crops) classified using temporally concurrent Landsat images compared to the standard method that relies on infrequently updated land use survey (LUS) crop data. The Landsat method can be used in epidemiologic studies to reconstruct past individual-level exposure to specific pesticides according to where individuals are located.

New insights into grocery store visits among east Los Angeles residents using mobility data.

In this study, we employed spatially aggregated population mobility data, generated from mobile phone locations in 2021, to investigate patterns of grocery store visits among residents east and northeast of Downtown Los Angeles, in which 60% of the census tracts had previously been designated as "food deserts". Further, we examined whether the store visits varied with neighborhood sociodemographics and grocery store accessibility. We found that residents averaged 0.4 trips to grocery stores per week, with only 13% of these visits within home census tracts, and 40% within home and neighboring census tracts. The mean distance from home to grocery stores was 2.2 miles. We found that people visited grocery stores more frequently when they lived in neighborhoods with higher percentages of Hispanics/Latinos, renters and foreign-born residents, and a greater number of grocery stores. This research highlights the utility of mobility data in elucidating grocery store use, and factors that may facilitate or be a barrier to store access. The results point to limitations of using geographically constrained metrics of food access like food deserts.

Global latitudinal gradients and the evolution of body size in dinosaurs and mammals.

Global climate patterns fundamentally shape the distribution of species and ecosystems. For example, Bergmann's rule predicts that homeothermic animals, including birds and mammals, inhabiting cooler climates are generally larger than close relatives from warmer climates. The modern world, however, lacks the comparative data needed to evaluate such macroecological rules rigorously. Here, we test for Bergmann's rule in Mesozoic dinosaurs and mammaliaforms that radiated within relatively temperate global climate regimes. We develop a phylogenetic model that accounts for biases in the fossil record and allows for variable evolutionary dispersal rates. Our analysis also includes new fossil data from the extreme high-latitude Late Cretaceous Arctic Prince Creek Formation. We find no evidence for Bergmann's rule in Mesozoic dinosaurs or mammaliaforms, the ancestors of extant homeothermic birds and mammals. When our model is applied to thousands of extant dinosaur (bird) and mammal species, we find that body size evolution remains independent of latitude. A modest temperature effect is found in extant, but not in Mesozoic, birds, suggesting that body size evolution in modern birds was influenced by Bergmann's rule during Cenozoic climatic change. Our study provides a general approach for studying macroecological rules, highlighting the fossil record's power to address longstanding ecological principles.