@article{braniecki_surge_hyland_goodwin_2024, title={Reconstructed seasonality during the Mid Piacenzian Warm Interval and early Pleistocene cooling as recorded by growth temperatures from <i>Mercenaria</i> shells}, volume={328}, ISSN={["1873-457X"]}, DOI={10.1016/j.quascirev.2024.108524}, abstractNote={The Mid Piacenzian Warm Interval (MPWI) has been identified as an analogue for future global warming because it had warmer temperatures and higher atmospheric CO2 levels than today, while subsequent early Pleistocene cooling is more similar to modern climate. However, reconstructions of these intervals lack seasonal-scale temperature reconstructions. Seasonal sea surface temperature (SST) reconstructions from deep-time archives can potentially provide insight into the nature of the climate system on sub-annual scales during critical climate states. Here we compared seasonal variability in growth temperatures during the MPWI and subsequent early Pleistocene cooling to modern climate reconstructed from oxygen isotope ratios recorded by the bivalve Mercenaria. Modern shells were collected from the University of North Carolina's Marine Sanctuary. Fossil shells from the Mid-Atlantic Coastal Plain (North Carolina) were collected from the Duplin Formation (MPWI) and the Waccamaw Formation (early Pleistocene). Oxygen isotope ratios range from −1 to 2.4 ‰ during the MPWI, −1–2.4 ‰ during the early Pleistocene, and −2.2 to 2.3 ‰ in modern shells. Stable carbon isotope ratios ranged from −0.91 to 1.67 ‰ during the MPWI, 0.19–1.87 ‰ during the early Pleistocene, and −2.46 to 0.60 ‰ in modern shells. Average seasonal growth temperature variations for the MPWI (∼11 ± 3 °C) are reduced compared to modern instrument records (∼16 ± 3 °C), while the early Pleistocene (∼14 ± 2 °C) was more similar to today. Modern Mercenaria record dark increment formation during the summer while fossil Mercenaria record dark increment formation during the winter. We hypothesize that this difference is timing of dark increment formation may be due in part to differences in water depth (∼1m for modern shells and ∼20m for fossil shells) or a shift in the location of the boundary between biogeographic zones. A −1.6 ‰ shift in mean stable carbon isotope ratios between fossil (0.92 ± 0.66 ‰) and modern (−0.65 ± 0.44 ‰) shells has been observed and may be a result of the “Suess Effect” and/or influences of estuarine/freshwater relative to marine settings.}, journal={QUATERNARY SCIENCE REVIEWS}, author={Braniecki, Garrett F. N. and Surge, Donna and Hyland, Ethan G. and Goodwin, David H.}, year={2024}, month={Mar} }
 @article{peck_inamdar_kan_peipoch_gold_merritts_walter_hyland_wegmann_yaculak_et al._2023, title={Back from the past? Assessment of nitrogen removal ability of buried historic wetland soils before and after a 1-year incubation on a restored floodplain}, volume={12}, ISSN={["1526-100X"]}, DOI={10.1111/rec.14070}, abstractNote={Stream, floodplain, and wetland restorations enhance water quality and ecological function; however, soil health is prioritized infrequently in restoration planning and monitoring. Buried, historic, hydric soils—common across U.S. mid‐Atlantic valley bottoms beneath legacy sediments—are not included in most floodplain restoration designs, though they may retain favorable biogeochemical characteristics and host legacy microbial communities that could support ecosystem recovery if exhumed and preserved. To assess the efficacy of including historic hydric soils in floodplain restoration for nitrogen (N) removal, we characterized pre‐Euro‐American settlement wetland soils buried below legacy sediments and now exposed along incised streambanks across the mid‐Atlantic. We compared carbon (C) and N contents; C:N ratios; nitrate‐N and ammonium‐N concentrations; denitrification rates; functional genes for denitrification (nosZ) and nitrification (amoA for ammonia oxidizing archaea [AoA] + ammonia oxidizing bacteria [AoB]); and phospholipid fatty acid biomasses of historic wetland soils with contemporary wetland soils before and after an 1‐year incubation in a recently restored floodplain. Compared to modern wetland soils, historic hydric soils buried by legacy sediment are less nutrient‐rich, have fewer functional genes for and lower rates of denitrification, and possess significantly less microbial biomass. Following the 1‐year incubation, many of these concentrations, rates, and gene counts increased in historic soils, though not substantially. Ultimately, our results suggest that while inclusion of historic, hydric soils and their legacy microbiomes is valuable for N‐removal in floodplain restoration, the recovery of historic, hydric soils is predictably slow, and attainment of restoration goals, such as increased denitrification, may require multiple years.}, journal={RESTORATION ECOLOGY}, author={Peck, Erin K. and Inamdar, Shreeram and Kan, Jinjun and Peipoch, Marc and Gold, Arthur J. and Merritts, Dorothy J. and Walter, Robert C. and Hyland, Ethan G. and Wegmann, Karl W. and Yaculak, Alexis M. and et al.}, year={2023}, month={Dec} }
 @article{burgener_hyland_reich_scotese_2023, title={Cretaceous climates: Mapping paleo-Koppen climatic zones using a Bayesian statistical analysis of lithologic, paleontologic, and geochemical proxies}, volume={613}, ISSN={["1872-616X"]}, DOI={10.1016/j.palaeo.2022.111373}, abstractNote={The Cretaceous Period (145 to 66 Ma) was a prolonged warmhouse to hothouse period characterized by high atmospheric CO2 conditions, elevated surface temperatures, and an enhanced global hydrologic cycle. It provides a case study for understanding how a hothouse climate system operates, and is an analog for future anthropogenic climate change scenarios. This study presents new quantitative temperature and precipitation proxy datasets for nine key Cretaceous time slices (Berriasian/Valanginian, Hauterivian/Barremian, Aptian, Albian, Cenomanian, Turonian, Coniacian/Santonian, Campanian, Maastrichtian), and a new geostatistical analysis technique that utilizes Markov Chain Monte Carlo algorithm and Bayesian hierarchical models to generate high resolution, quantitative global paleoclimate reconstructions from these proxy datasets, with associated uncertainties. Using these paleoclimate reconstructions, paleo-Köppen (-Geiger) climate zone maps are produced that provide new insights into the changing spatial and temporal climate patterns during the Cretaceous. These new paleoclimate reconstructions and paleo-Köppen climate maps provide new insight into the timing of the initiation of the Early Cretaceous equatorial humid belt over Gondwana and reveal temporal shifts in the width of the subtropical arid belts from the Early to mid- to Late Cretaceous. A comparison of these proxy-based reconstructions and model simulations of Cretaceous climate reveal continued proxy/model differences. In addition, the methodology developed for this study can be applied to other time periods, providing a framework for better understanding ancient climate, environments, and ecosystems.}, journal={PALAEOGEOGRAPHY PALAEOCLIMATOLOGY PALAEOECOLOGY}, author={Burgener, Landon and Hyland, Ethan and Reich, Brian J. and Scotese, Christopher}, year={2023}, month={Mar} }
 @article{padgett_hyland_west_burgener_greenwood_basinger_2023, title={Paleogene Paleohydrology of Ellesmere and Axel Heiberg Islands (Arctic Canada) From Palustrine Carbonates}, volume={38}, ISSN={["2572-4525"]}, DOI={10.1029/2023PA004609}, abstractNote={Abstract}, number={10}, journal={PALEOCEANOGRAPHY AND PALEOCLIMATOLOGY}, author={Padgett, Ashly B. and Hyland, Ethan G. and West, Christopher K. and Burgener, Landon K. and Greenwood, David R. and Basinger, James F.}, year={2023}, month={Oct} }
 @article{renaut_tucker_king_crowley_hyland_zanno_2023, title={Timing of the Greenhorn transgression and OAE2 in Central Utah using CA-TIMS U-Pb zircon dating}, volume={146}, ISSN={["1095-998X"]}, DOI={10.1016/j.cretres.2022.105464}, abstractNote={Contextualizing subbasinal influences on accommodation and pace of the rapid landscape evolution during the base-level rise of the Upper Cretaceous (upper Cenomanian–lower Turonian) Greenhorn Cycle within the Western Interior of North America requires refined stratigraphic controls of key sediment successions. Herein, a blended analysis of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), chemical abrasion thermal ionization mass spectrometry (CA-TIMS), and δ13C isotopic data is utilized to identify two regionally significant ash-fall marker beds southeast of the Wasatch Plateau, specifically the TT1 and TT4, which bracket the Cenomanian–Turonian boundary and the Greenhorn Cycle transgression in the Western Interior Seaway (WIS). Based on our analysis of the recovered ash-fall zircons, a meaningful depositional age (DA) for the TT1 is 94.616 Ma ± 0.027 and 94.010 Ma ± 0.017 for the TT4 bentonite of the Tununk Shale. When coupled with the pre-existing biostratigraphic framework, correlation potential greatly increases with the (TT1) Naturita falling within the Sciponoceras gracile Assemblage Zone. Common molluscs associated with this biozone within the southern and central regions of Utah include Inoceramus pictus, Euomphaloceras spp., and Pycnodonte newberryi. The (TT4) Tununk within the upper portion of the Watinoceras coloradoense Assemblage Zone is commonly associated with the following mollusc genus within the areas to the south and north of the study area: Mytiloides and Morrowites. Furthermore, these dates constrain the Cenomanian–Turonian boundary, provide accurate chronostratigraphic markers for intra and interbasinal correlation and serve to strengthen global linkages to Ocean Anoxic Event 2 (OAE2) during the Greenhorn Cycle transgression.}, journal={CRETACEOUS RESEARCH}, author={Renaut, Ray K. and Tucker, Ryan T. and King, M. Ryan and Crowley, James L. and Hyland, Ethan G. and Zanno, Lindsay E.}, year={2023}, month={Jun} }
 @article{honisch_royer_breecker_polissar_bowen_henehan_cui_steinthorsdottir_mcelwain_kohn_et al._2023, title={Toward a Cenozoic history of atmospheric CO<sub>2</sub> The Cenozoic CO<sub>2</sub> Proxy Integration Project (CenCO<sub>2</sub>PIP) Consortium}, volume={382}, ISSN={["1095-9203"]}, DOI={10.1126/science.adi5177}, abstractNote={
            The geological record encodes the relationship between climate and atmospheric carbon dioxide (CO
            2
            ) over long and short timescales, as well as potential drivers of evolutionary transitions. However, reconstructing CO
            2
            beyond direct measurements requires the use of paleoproxies and herein lies the challenge, as proxies differ in their assumptions, degree of understanding, and even reconstructed values. In this study, we critically evaluated, categorized, and integrated available proxies to create a high-fidelity and transparently constructed atmospheric CO
            2
            record spanning the past 66 million years. This newly constructed record provides clearer evidence for higher Earth system sensitivity in the past and for the role of CO
            2
            thresholds in biological and cryosphere evolution.
          }, number={6675}, journal={SCIENCE}, author={Honisch, Barbel and Royer, Dana L. and Breecker, Daniel O. and Polissar, Pratigya J. and Bowen, Gabriel J. and Henehan, Michael J. and Cui, Ying and Steinthorsdottir, Margret and McElwain, Jennifer C. and Kohn, Matthew J. and et al.}, year={2023}, month={Dec}, pages={1136-+} }
 @article{raigemborn_lizzoli_hyland_cotton_peral_beilinson_krause_2022, title={A paleopedological approach to understanding Eocene environmental conditions in southern Patagonia, Argentina}, volume={601}, ISSN={["1872-616X"]}, DOI={10.1016/j.palaeo.2022.111129}, abstractNote={The Eocene Las Flores and Koluel-Kaike formations in southern Patagonia (~48° S, Golfo San Jorge Basin, Argentina) are pedogenically modified fluvial and fluvio-eolian successions, respectively, which document early-middle Eocene environments at mid-paleolatitudes in the Southern Hemisphere. In order to reconstruct the paleoenvironment for the Las Flores and Koluel-Kaike formations, we performed a multiproxy and coordinated study of sediments and paleosols of both units, considering abiotic components. Using detailed sedimentology and paleopedology (macro- and micromorphology), bulk paleosol geochemistry and clay mineralogy, and organic carbon concentrations and stable isotope (δ13Corg) compositions, we show that the Las Flores and Koluel-Kaike paleosols are overall Ultisol-like paleosols, mineralogically and chemically consistent with a high to high-moderate degree of weathering, and developed on different parent materials (sedimentary with sandy and silty texture vs. silty volcaniclastic). Climate proxies and a comparison with modern Ultisols with similar features suggest that these paleosols formed under a broadly tropical-temperate and humid-subhumid climate with distinct seasonality. Overall, these combined data record long-term environmental conditions during the Paleogene (early-middle Eocene), and preserve a record of Eocene terrestrial climate in the Southern Hemisphere. This research is relevant for understanding latitudinal climatic gradients during warm periods like the Eocene, a key knowledge gap for future predictions, and these sites are particularly important because mid-latitude reconstructions in the Southern Hemisphere are the poorest resolved.}, journal={PALAEOGEOGRAPHY PALAEOCLIMATOLOGY PALAEOECOLOGY}, author={Raigemborn, M. Sol and Lizzoli, Sabrina and Hyland, Ethan and Cotton, Jennifer and Peral, Lucia E. Gomez and Beilinson, Elisa and Krause, J. Marcelo}, year={2022}, month={Sep} }
 @article{tucker_hyland_gates_king_roberts_foley_berndt_hanta_khansubha_aswasereelert_et al._2022, title={Age, depositional history, and paleoclimatic setting of Early Cretaceous dinosaur assemblages from the Sao Khua Formation (Khorat Group), Thailand}, volume={601}, ISSN={["1872-616X"]}, DOI={10.1016/j.palaeo.2022.111107}, abstractNote={We describe the sedimentology, geochronology, and geochemistry of the Early Cretaceus Sao Khua Formation of the Khorat Basin, northeastern Thailand, and report a temporal range adjustment for its dinosaurian assemblage. Facies analysis and architectural studies reveal that sedimentation occurred within a floodplain setting fed by large meandering bedload-rich channels. Interfluve areas comprised freshwater lakes and emergent areas subject to pedogenic modification. Multiple paleosol types are identified and geochemistry is indicative of a stable humid subtropical climate regime. Based on radiometric dating of detrital zircons (via LA-ICP-MS), we interpret that the middle part of the Sao Khua Formation was deposited no later than 133.8 (±1.8) Ma (late Valanginian), and grain ages collected from the overlying lowermost Phu Phan Fm constrain sedimentation of the upper part of the Sao Khua Formation to no earlier than 132.4 (±2.0) Ma (early Hauterivian). In consideration of the Early Cretaceous regional tectonic framework, we interpret that youthful igneous zircon grains are derived from the adjacent South China-Vietnam South Borneo Volcanic Arc. We establish that the entombed dinosaur biota (including members of the Ornithomimosauria, Spinosauridae, Megaraptora, and Somphospondylia) is ~5–9 million years older than previously recognized and that these records are among the oldest known globally for these clades. Constraining the age of the Sao Khua Formation indicates that the shift from sauropod-dominated, ornithischian depauperate ecosystems of the Sao Khua Formation to iguanodontian-rich ecosystems of the Khok Kruat Formation occurred sometime between the early Hauterivian and Aptian on the Khorat Plateau.}, journal={PALAEOGEOGRAPHY PALAEOCLIMATOLOGY PALAEOECOLOGY}, author={Tucker, Ryan T. and Hyland, Ethan G. and Gates, Terry A. and King, M. Ryan and Roberts, Eric M. and Foley, Elliot K. and Berndt, David and Hanta, Rattanaphorn and Khansubha, Sasa-on and Aswasereelert, Wasinee and et al.}, year={2022}, month={Sep} }
 @article{riegel_casale_mirabella_hyland_talegalli_2022, title={Deep External Fluid Source Along the Gubbio Normal Fault (Italy): Implications for Slip Along the Altotiberina Active Low-Angle Normal Fault System}, volume={10}, ISSN={["2296-6463"]}, DOI={10.3389/feart.2022.811339}, abstractNote={Fluids play a critical role in fault slip, fault and damage zone development, and the distribution of seismicity in regional fault systems; however, determining the source of fluids within fault damage zones is complicated by superposition of fluid-related fabrics. Clumped isotopes applied to tectonic studies offer an opportunity to distinguish between fluid sources based on temperature and stable isotopic composition. Here we use the clumped isotope geothermometer and field observations and compare them with microstructural analysis to investigate the Gubbio normal-fault (GuF) core, a major SW-dipping epidetachment fault conjugate to the active Altotiberina low-angle normal fault in central Italy. Several distinct calcite vein sets reveal the incorporation of multiple generations of fluids during development of the damage zone. Clumped isotope results from these various precipitation phases record crystallization temperatures ranging from 87–154°C. These temperatures are broadly consistent with the presence of calcite deformation twin types II and III and are higher than estimates of regional peak burial temperatures. Additionally, stable isotope compositions within vein calcite are distinct from published isotopic values of the Apennine sedimentary succession, which constitutes the local bedrock. We propose that these observations suggest hydrothermal fluids migrated from depths greater than 6 km, which requires hydraulic connectivity along structural pathways between the shallow and deep crust, and fluid overpressures. These fluids reach the GuF via migration along the Altotiberina low-angle normal fault plane ​​and they may be either of diagenetic or of deeper subduction origin. We suggest they possibly originated from the proximal retreating Apennine subduction system, implying that subduction processes exert spatial control on the distribution of fluid-assisted normal faulting and related seismicity which is consistent with the co-migration of closely coupled subduction and hinterland extension in the Apennines from Miocene to Present.}, journal={FRONTIERS IN EARTH SCIENCE}, author={Riegel, Hannah and Casale, Gabriele and Mirabella, Francesco and Hyland, Ethan and Talegalli, Lorenzo}, year={2022}, month={Feb} }
 @article{gates_cai_hu_han_griffith_burgener_hyland_zanno_2022, title={Estimating ancient biogeographic patterns with statistical model discrimination}, volume={9}, ISSN={["1932-8494"]}, url={https://doi.org/10.1002/ar.25067}, DOI={10.1002/ar.25067}, abstractNote={Abstract}, journal={ANATOMICAL RECORD-ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY}, author={Gates, Terry A. and Cai, Hengrui and Hu, Yifei and Han, Xu and Griffith, Emily and Burgener, Landon and Hyland, Ethan and Zanno, Lindsay E.}, year={2022}, month={Sep} }
 @article{krings_szakacs_hyland_2022, title={Remnants of the "Grande Savane?" Insights from Soil Organic Matter at Two Sites in the Deep River Triassic Basin of North Carolina}, volume={87}, ISSN={["1938-4386"]}, DOI={10.2179/0008-7475.87.2.244}, abstractNote={ABSTRACT Narrative accounts and floristics suggest a broader historical distribution of Piedmont upland savannas and woodlands with a prairie-affinity flora than today, although dates of emergence, spatiotemporal extent, and historical dynamics remain unclear. To help address the question whether remnant prairie-affinity patches in the state represent at least historical, if not ancient, grasslands, we analyzed stable carbon isotopes from soil organic matter from two well-known localities hosting prairie-affinity heliophytes, both within the boundaries of historically mapped “Grande Savane”. Soil cores for δ13Corg analysis and radiocarbon dating were collected from five sites, hosting different present-day plant communities and spanning three soil orders. Recovered δ13Corg values suggest historical grasslands, likely savanna-type with some fluctuations in cover, were present at both localities essentially continuously over the past 2000 years until the more recent canopy closure over the past century. These findings are consistent with historical narrative accounts, although significant additional sampling is needed to determine its spatiotemporal extent. While the general trend at our localities transitions from open to closed systems, pronounced fluctuations are apparent in all profiles, particularly between 1254–1468 CE. Precipitation does not appear predominantly responsible, but available climatic reconstructions are from an adjacent basin. The timing of the pronounced vegetation class fluctuations is intriguingly coincidental to the timing of Siouan occupancy and intertribal movements, suggesting a need for more vigorous interdisciplinary investigations.}, number={2}, journal={CASTANEA}, author={Krings, Alexander and Szakacs, Alexandria D. and Hyland, Ethan G.}, year={2022}, month={Dec}, pages={244–267} }
 @article{burgener_hyland_griffith_mitasova_zanno_gates_2021, title={An extreme climate gradient-induced ecological regionalization in the Upper Cretaceous Western Interior Basin of North America}, volume={133}, ISSN={["1943-2674"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-85111073513&partnerID=MN8TOARS}, DOI={10.1130/B35904.1}, abstractNote={Abstract}, number={9-10}, journal={GEOLOGICAL SOCIETY OF AMERICA BULLETIN}, author={Burgener, Landon and Hyland, Ethan and Griffith, Emily and Mitasova, Helena and Zanno, Lindsay E. and Gates, Terry A.}, year={2021}, pages={2125–2136} }
 @article{bernasconi_daeron_bergmann_bonifacie_meckler_affek_anderson_bajnai_barkan_beverly_et al._2021, title={InterCarb: A Community Effort to Improve Interlaboratory Standardization of the Carbonate Clumped Isotope Thermometer Using Carbonate Standards}, volume={22}, ISSN={["1525-2027"]}, DOI={10.1029/2020GC009588}, abstractNote={Abstract}, number={5}, journal={GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS}, author={Bernasconi, S. M. and Daeron, M. and Bergmann, K. D. and Bonifacie, M. and Meckler, A. N. and Affek, H. P. and Anderson, N. and Bajnai, D. and Barkan, E. and Beverly, E. and et al.}, year={2021}, month={May} }
 @misc{heitmann_hyland_schoettle-greene_brigham_huntington_2021, title={Rise of the Colorado Plateau: A Synthesis of Paleoelevation Constraints From the Region and a Path Forward Using Temperature-Based Elevation Proxies}, volume={9}, ISSN={["2296-6463"]}, DOI={10.3389/feart.2021.648605}, abstractNote={The Colorado Plateau’s complex landscape has motivated over a century of debate, key to which is understanding the timing and processes of surface uplift of the greater Colorado Plateau region, and its interactions with erosion, drainage reorganization, and landscape evolution. Here, we evaluate what is known about the surface uplift history from prior paleoelevation estimates from the region by synthesizing and evaluating estimates 1) in context inferred from geologic, geomorphic, and thermochronologic constraints, and 2) in light of recent isotopic and paleobotanical proxy method advancements. Altogether, existing data and estimates suggest that half-modern surface elevations were attained by the end of the Laramide orogeny (∼40 Ma), and near-modern surface elevations by the mid-Miocene (∼16 Ma). However, our analysis of paleoelevation proxy methods highlights the need to improve proxy estimates from carbonate and floral archives including the ∼6–16 Ma Bidahochi and ∼34 Ma Florissant Formations and explore understudied (with respect to paleoelevation) Laramide basin deposits to fill knowledge gaps. We argue that there are opportunities to leverage recent advancements in temperature-based paleoaltimetry to refine the surface uplift history; for instance, via systematic comparison of clumped isotope and paleobotanical thermometry methods applied to lacustrine carbonates that span the region in both space and time, and by use of paleoclimate model mediated lapse rates in paleoelevation reconstruction.}, journal={FRONTIERS IN EARTH SCIENCE}, author={Heitmann, Emma O. and Hyland, Ethan G. and Schoettle-Greene, Philip and Brigham, Cassandra A. P. and Huntington, Katharine W.}, year={2021}, month={Jun} }
 @article{hyland_sheldon_smith_stromberg_2019, title={Late Miocene rise and fall of C-4 grasses in the western United States linked to aridification and uplift}, volume={131}, ISSN={["1943-2674"]}, DOI={10.1130/B32009.1}, abstractNote={Research Article| August 15, 2018 Late Miocene rise and fall of C4 grasses in the western United States linked to aridification and uplift Ethan G. Hyland; Ethan G. Hyland † 1Department of Earth and Environmental Sciences, University of Michigan, 1100 North University Avenue, Ann Arbor, Michigan 48109, USA2Department of Biology and Burke Museum of Natural History, University of Washington, Seattle, Washington 98195, USA †Present address: MEAS, North Carolina State University; ehyland@ncsu.edu. Search for other works by this author on: GSW Google Scholar Nathan D. Sheldon; Nathan D. Sheldon 1Department of Earth and Environmental Sciences, University of Michigan, 1100 North University Avenue, Ann Arbor, Michigan 48109, USA Search for other works by this author on: GSW Google Scholar Selena Y. Smith; Selena Y. Smith 1Department of Earth and Environmental Sciences, University of Michigan, 1100 North University Avenue, Ann Arbor, Michigan 48109, USA Search for other works by this author on: GSW Google Scholar Caroline A.E. Strömberg Caroline A.E. Strömberg 2Department of Biology and Burke Museum of Natural History, University of Washington, Seattle, Washington 98195, USA Search for other works by this author on: GSW Google Scholar GSA Bulletin (2019) 131 (1-2): 224–234. https://doi.org/10.1130/B32009.1 Article history received: 04 Jan 2018 rev-recd: 17 May 2018 accepted: 16 Jul 2018 first online: 15 Aug 2018 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Ethan G. Hyland, Nathan D. Sheldon, Selena Y. Smith, Caroline A.E. Strömberg; Late Miocene rise and fall of C4 grasses in the western United States linked to aridification and uplift. GSA Bulletin 2018;; 131 (1-2): 224–234. doi: https://doi.org/10.1130/B32009.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract C4 grasslands are a major global ecosystem with an important role as the primary source of food resources and agricultural land for the planet. Despite this, the causes and timeline of their expansion are still not fully known and appear to be variable in different parts of the world. By combining phytolith and stable isotope methods, we produce robust estimates of late Miocene C4 vegetation composition and compile a regional vegetation record through time from the late Miocene through present in southwestern Montana (USA). These estimates indicate the fairly rapid rise of C4 grasses to peak levels during the late Miocene (Hemphillian) and subsequent decline to moderate levels from the Pliocene through Present. This temporal pattern indicates significant interplay between climatic and tectonic drivers, with the late Miocene rise of C4 grasses triggered by regional aridification, and the return to lower (modern) abundances due to ecosystem restrictions linked to recent regional uplift driven by mantle buoyancy associated with the Yellowstone hotspot. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.}, number={1-2}, journal={GEOLOGICAL SOCIETY OF AMERICA BULLETIN}, author={Hyland, Ethan G. and Sheldon, Nathan D. and Smith, Selena Y. and Stromberg, Caroline A. E.}, year={2019}, pages={224–234} }
 @article{burgener_hyland_huntington_kelson_sewall_2019, title={Revisiting the equable climate problem during the Late Cretaceous greenhouse using paleosol carbonate clumped isotope temperatures from the Campanian of the Western Interior Basin, USA}, volume={516}, ISSN={["1872-616X"]}, DOI={10.1016/j.palaeo.2018.12.004}, abstractNote={Greenhouse climates such as the Late Cretaceous period provide important reference frames for understanding modern anthropogenic climate change. Upper Cretaceous terrestrial climate proxies have been interpreted as evidence for “equable” climates with reduced seasonal variations in temperature. However, climate models have largely failed to reproduce these reconstructions unless parameters such as atmospheric CO2 concentrations are set to unreasonable values. To help resolve such model-proxy disagreements, we reconstruct mean annual range in temperature (MART) for the Campanian (~75 Ma) Kaiparowits (south-central Utah) and Two Medicine (northwest Montana) Formations using warmest mean monthly temperature reconstructions from the clumped isotope composition of paleosol carbonate nodules, and reconstructions of local mean annual air temperatures from other methods. An evaluation of the applicability of bulk elemental soil geochemistry temperature proxies in these deposits supports the use of previous leaf physiognomy-based estimates of mean annual temperature for our MART reconstructions. We test the validity of several common assumptions made in reconstructing MART in two novel ways. First, MART is commonly calculated as twice the difference between local mean annual air temperature and warmest mean monthly temperature, and we validate this method by estimating modern MART for a range of environments using climate reanalysis data. Second, we constrain the effect of radiative soil heating on our soil carbonate temperature estimates by showing that for most environments likely to be preserved in the geologic record, summer soil temperatures are <3 °C higher than air temperatures. Our findings suggest that warmest mean monthly temperatures were 30 to 35 ± 4 °C at the two study sites, and that MART was 21 to 29 °C for the Kaiparowits Formation, and 21 to 27 °C for the Two Medicine Formation. Mid-latitude Late Cretaceous MARTs were similar to modern ranges in mid-latitude seasonal temperature, and much (>9 °C) larger than previous proxy reconstructions of Late Cretaceous MART. These results add to a growing body of literature showing that terrestrial MART during ancient greenhouse periods was not significantly different from modern seasonal temperature variations. Finally, the similarity in MART between the Kaiparowits and Two Medicine formations suggests that latitudinal changes in MART did not contribute to the faunal provincialism that has been proposed by some paleontologists.}, journal={PALAEOGEOGRAPHY PALAEOCLIMATOLOGY PALAEOECOLOGY}, author={Burgener, Landon and Hyland, Ethan and Huntington, Katharine W. and Kelson, Julia R. and Sewall, Jacob O.}, year={2019}, month={Feb}, pages={244–267} }
 @article{parrish_hyland_chan_hasiotis_2019, title={Stable and clumped isotopes in desert carbonate spring and lake deposits reveal palaeohydrology: A case study of the Lower Jurassic Navajo Sandstone, south-western USA}, volume={66}, ISSN={["1365-3091"]}, DOI={10.1111/sed.12540}, abstractNote={Abstract}, number={1}, journal={SEDIMENTOLOGY}, author={Parrish, Judith Totman and Hyland, Ethan G. and Chan, Marjorie A. and Hasiotis, Stephen T.}, year={2019}, month={Jan}, pages={32–52} }
 @article{hyland_sheldon_2018, title={Comment on "Paleosol-based paleoclimate reconstruction of the Paleocene-Eocene Thermal Maximum, northern Argentina" by Andrews, E., White, T., and del Papa, C. [Palaeogeography, Palaeoclimatology, Palaeoecology, v. 471, p. 181-195]}, volume={511}, ISSN={["1872-616X"]}, DOI={10.1016/j.palaeo.2017.05.031}, abstractNote={Andrews et al. (2017) present a paleosol-based paleoclimate reconstruction of the Paleocene-Eocene Thermal Maximum from localities in northern Argentina. We suggest that the age model presented for these localities is incorrect based on recently published magnetostratigraphy from the area, and that the studied Maiz Gordo and Lumbrera Formations instead represent a paleoclimate record of the early to middle Eocene. This record, combined with previously published data from these formations provide a more comprehensive regional reconstruction of paleoclimate and paleoenvironmental conditions during the peak of early Eocene warmth, including the early Eocene climatic optimum and possibly the middle Eocene climatic optimum.}, journal={PALAEOGEOGRAPHY PALAEOCLIMATOLOGY PALAEOECOLOGY}, author={Hyland, Ethan G. and Sheldon, Nathan D.}, year={2018}, month={Dec}, pages={639–642} }
 @article{smiley_hyland_cotton_reynolds_2018, title={Evidence of early C4 grasses, habitat heterogeneity, and faunal response during the Miocene Climatic Optimum in the Mojave Region}, volume={490}, ISSN={0031-0182}, url={http://dx.doi.org/10.1016/J.PALAEO.2017.11.020}, DOI={10.1016/J.PALAEO.2017.11.020}, abstractNote={Major changes to landscapes, climate, and mammalian faunas occurred at the regional scale in western North America during the Miocene Climatic Optimum (MCO) between ~17 and 14 Ma, but few studies have looked at how the MCO affected basin-scale environments. Paleoenvironmental reconstructions coupled with mammalian fossil assemblages from the Crowder and Cajon Valley formations in the Mojave Desert, California, contribute insights into local-scale (10s of kilometers) responses to warming during the Hemingfordian and Barstovian North American Land Mammal Ages. By integrating lithological descriptions, phytolith analyses, carbon isotope composition of preserved soil organic matter (δ13CSOM), and elemental geochemistry of paleosols, we provide reconstructions of depositional environments, vegetation, and precipitation through the MCO. Phytolith and δ13CSOM evidence suggest that paleoenvironments were predominately C3 grasslands, with the earliest potential presence of C4 grasses in the region found within the Crowder Formation at ~17 Ma. Based on elemental geochemistry of paleosols, mean annual precipitation estimates are 807 (±182) mm yr− 1 at 17 Ma in the Crowder Formation and 740–800 (±182) mm yr− 1 from 16 to 15 Ma in the Cajon Valley Formation. Our multiproxy approach indicates that the Crowder and Cajon Valley basins were stable, large-scale braided stream and floodplain systems with intermittent paleosol development and heterogeneity in vegetation and moisture conditions across spatial scales. Overall, we find a signal of local paleoenvironmental stability during the MCO; however, a significant drying trend in the Crowder Formation does correspond with faunal turnover and reduction in the number of taxa present. High species diversity within faunal assemblages, especially among small mammals, and fewer shared species between the Crowder and Cajon Valley assemblages than expected based on bootstrap analysis indicate that peak mammal diversity was accommodated at both local and regional scales during sustained tectonic activity and the MCO in western North America.}, journal={Palaeogeography, Palaeoclimatology, Palaeoecology}, publisher={Elsevier BV}, author={Smiley, Tara M. and Hyland, Ethan G. and Cotton, Jennifer M. and Reynolds, Robert E.}, year={2018}, month={Jan}, pages={415–430} }
 @article{hyland_huntington_sheldon_reichgelt_2018, title={Temperature seasonality in the North American continental interior during the Early Eocene Climatic Optimum}, volume={14}, ISSN={["1814-9332"]}, DOI={10.5194/cp-14-1391-2018}, abstractNote={Abstract. Paleogene greenhouse climate equability has long been a paradox in paleoclimate research. However, recent developments in proxy and modeling methods have suggested that strong seasonality may be a feature of at least some greenhouse Earth periods. Here we present the first multi-proxy record of seasonal temperatures during the Paleogene from paleofloras, paleosol geochemistry, and carbonate clumped isotope thermometry in the Green River Basin (Wyoming, USA). These combined temperature records allow for the reconstruction of past seasonality in the continental interior, which shows that temperatures were warmer in all seasons during the peak Early Eocene Climatic Optimum and that the mean annual range of temperatures was high, similar to the modern value ( ∼ 26 °C). Proxy data and downscaled Eocene regional climate model results suggest amplified seasonality during greenhouse events. Increased seasonality reconstructed for the early Eocene is similar in scope to the higher seasonal range predicted by downscaled climate model ensembles for future high-CO2 emissions scenarios. Overall, these data and model comparisons have substantial implications for understanding greenhouse climates in general, and may be important for predicting future seasonal climate regimes and their impacts in continental regions.
                    }, number={10}, journal={CLIMATE OF THE PAST}, author={Hyland, Ethan G. and Huntington, Katharine W. and Sheldon, Nathan D. and Reichgelt, Tammo}, year={2018}, month={Oct}, pages={1391–1404} }
 @article{kelson_watford_bataille_huntington_hyland_bowen_2018, title={Warm Terrestrial Subtropics During the Paleocene and Eocene: Carbonate Clumped Isotope (Delta(47)) Evidence From the Tornillo Basin, Texas (USA)}, volume={33}, ISSN={["2572-4525"]}, DOI={10.1029/2018PA003391}, abstractNote={Abstract}, number={11}, journal={PALEOCEANOGRAPHY AND PALEOCLIMATOLOGY}, author={Kelson, Julia R. and Watford, Dylana and Bataille, Clement and Huntington, Katharine W. and Hyland, Ethan and Bowen, Gabriel J.}, year={2018}, month={Nov}, pages={1230–1249} }
 @article{hyland_sheldon_cotton_2015, title={Terrestrial evidence for a two-stage mid-Paleocene biotic event}, volume={417}, ISSN={0031-0182}, url={http://dx.doi.org/10.1016/J.PALAEO.2014.09.031}, DOI={10.1016/J.PALAEO.2014.09.031}, abstractNote={Marine records of the Paleocene indicate a series of hyperthermal events characterized by significant climatic and carbon cycle variability, but there are few comparable continental records. The mid-Paleocene biotic event (MPBE) is a recently described interval defined by a rapid negative carbon isotope excursion and major short-term changes in marine ecosystems, but it is as yet unclear whether the event was globally important. Here we present the first terrestrial paleoenvironmental record of the MPBE based on paleosols that document rapid and short-lived increases in temperature and precipitation and resultant shifts in plant assemblages concomitant with substantial carbon isotope excursions. The new record indicates that carbon cycle changes during the early late Paleocene may have resulted in a two-stage transient hyperthermal event that caused a significant perturbation to both the regional climate and terrestrial ecology of South America in addition to the major biotic event (MPBE) previously recognized in marine records. Overall, this suggests that the MPBE may have been a global climate event with far-reaching environmental impacts in both the marine and terrestrial realms.}, journal={Palaeogeography, Palaeoclimatology, Palaeoecology}, publisher={Elsevier BV}, author={Hyland, Ethan G. and Sheldon, Nathan D. and Cotton, Jennifer M.}, year={2015}, month={Jan}, pages={371–378} }
 @article{cotton_hyland_sheldon_2014, title={Multi-proxy evidence for tectonic control on the expansion of C4 grasses in northwest Argentina}, volume={395}, ISSN={0012-821X}, url={http://dx.doi.org/10.1016/J.EPSL.2014.03.014}, DOI={10.1016/J.EPSL.2014.03.014}, abstractNote={The timing of the rise of C4 grasses and the climatic conditions driving their expansion are widely debated, with recent studies suggesting that the expansion was more complex than previously thought. Proxy reconstructions from northwestern Argentina record multiple increases and decreases in C4 abundance throughout the late Miocene to early Pliocene, as well as variations in the timing of the spread of C4 grasses into the region. Here we present a multi-proxy paleovegetation reconstruction of the proportions of C3 and C4 vegetation using organic carbon and phytoliths preserved in paleosols at Entre Ríos in the Santa María Basin of Catamarca, Argentina between 6.2 and 3.3 Ma. Both δCorg13 and phytolith assemblages indicate a C3 dominated ecosystem with no evidence for substantial amounts of C4 vegetation from the late Miocene through mid-Pliocene, despite their rise to dominance elsewhere during this time. These data suggest that by 6.2 Ma the Santa María basin floor was at an elevation high enough to create locally cool conditions that allowed C3 vegetation to outcompete C4 grasses. Phytolith assemblages show that later uplift of the Sierra Calchaquies and Sierra Aconquija ranges through the Pliocene increased aridity and drove the expansion of C3 grasses at the expense of palms and other forest indicators. This multi-proxy paleovegetation reconstruction demonstrates that tectonics played an important role in controlling the late Miocene expansion C4 grasses by suppressing their spread into northwest Argentina.}, journal={Earth and Planetary Science Letters}, publisher={Elsevier BV}, author={Cotton, Jennifer M. and Hyland, Ethan G. and Sheldon, Nathan D.}, year={2014}, month={Jun}, pages={41–50} }
 @article{hyland_sheldon_2013, title={Coupled CO2-climate response during the Early Eocene Climatic Optimum}, volume={369}, ISSN={0031-0182}, url={http://dx.doi.org/10.1016/j.palaeo.2012.10.011}, DOI={10.1016/j.palaeo.2012.10.011}, abstractNote={The Early Eocene Climatic Optimum (EECO) has been characterized as a prolonged warm event indicated by increased atmospheric pCO2, temperatures, precipitation, and biological turnover. A new paleoenvironmental reconstruction using integrated pedological, geochemical, and isotopic data from the Green River Basin (Green River/Great Divide region) provides a high-resolution record of environmental and climatic change throughout the EECO. Our reconstruction indicates that this region, and likely much of the margin of paleolake Gosiute, was a stable, fluvially-controlled floodplain environment with evidence of large scale continuous soil development and features comparable with modern Alfisols (temperate forest soils). Regional climate data from multiple proxies indicates that the period was warm-temperate and semi-arid to sub-humid, with a peak interval from about 51.5–50.9 Ma that exhibits significantly warmer (~ 7 °C) and wetter (~ 750 mm yr− 1) conditions, resulting in major changes to the local weathering regime. Isotopic analyses also indicate a rapid increase to high atmospheric pCO2 values (~ 1700 ppmV) and a shift in the δ13C composition of pedogenic carbonates during this peak interval that appear to define and provide a cause for this significant regional response to global climatic change. The new data, when combined with foraminiferal δ13C records, are consistent with CO2 ventilation from a deep marine reservoir source. This multi-proxy reconstruction suggests that the EECO may have had a superimposed “peak” of climatic and ecological change on land.}, journal={Palaeogeography, Palaeoclimatology, Palaeoecology}, publisher={Elsevier BV}, author={Hyland, Ethan G. and Sheldon, Nathan D.}, year={2013}, month={Jan}, pages={125–135} }
 @article{hyland_smith_sheldon_2013, title={Representational bias in phytoliths from modern soils of central North America: Implications for paleovegetation reconstructions}, volume={374}, ISSN={0031-0182}, url={http://dx.doi.org/10.1016/J.PALAEO.2013.01.026}, DOI={10.1016/J.PALAEO.2013.01.026}, abstractNote={Understanding localized patterns and community compositions of vegetation in an environment is critical to the reconstruction of climatic and ecological conditions across all spatiotemporal scales. One of the most accurate and useful ways to characterize vegetation, and therefore to describe the climatic and ecological conditions of a location, is through the plant fossil record. Phytoliths (plant silica microfossils) are often preserved in the absence of other paleobotanical data and are becoming more widely used for deep-time vegetation reconstructions. Significant work has been done to standardize the analytical methodology of phytolith extraction, statistical analysis, and interpretation, but more detailed investigations are needed to understand how well a given soil assemblage represents the actual aboveground plant biomass for a given ecosystem. We present results from paired soil phytolith assemblages and local vegetation assemblages across the central United States, including temperate forest, grassland, and rangeland/scrubland ecosystems. Phytolith assemblages obtained via extractions from soil A-horizons were compared to percent cover of species and plant biomass estimates obtained via in situ field observations and aerial estimates of tree cover to analyze differences in the relative abundance of forest/woody vegetation vs. grasses. Soil phytolith assemblages from all sites average a 29% bias toward the grass morphotypes as compared to actual aboveground biomass observations, and comparisons to percent cover yielded broadly comparable bias figures. Percent bias estimates do not show significant correlations to most environmental factors (temperature, precipitation, local elevation), however, an extremely strong correlation (p < 0.001) was observed with soil order type. This is likely due to the fact that soil order reflects both vegetation type and chemical factors known to affect overall phytolith assemblages; therefore, soil order is a proxy that aggregates several sources of bias. As a result, we suggest further research into the development of correction factors between phytolith sample assemblages and their interpreted past counterpart ecosystems based on estimates derived from modern analyses of each major soil order type. Such background corrections are essential to the continued use of phytoliths as a proxy for past vegetation and ecological reconstructions of temperate ecosystems throughout the Phanerozoic record.}, journal={Palaeogeography, Palaeoclimatology, Palaeoecology}, publisher={Elsevier BV}, author={Hyland, Ethan and Smith, Selena Y. and Sheldon, Nathan D.}, year={2013}, month={Mar}, pages={338–348} }