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North America contains abundant Cretaceous continental strata that hosts potential archives of paleoclimate records. While detailed work has been done in Late Cretaceous strata which not only contains archives for stable isotope proxies, but also leaf physiognomic work, less study has occurred in the Early Cretaceous which lack angiosperm-dominated floras. Here we present new paleotemperature estimates from multiple stable isotope proxies including d18O of pedogenic carbonates, clumped isotope paleothermometry, and paired stable isotopes of aquatic and semi-aquatic taxa. The southern-most data originate from the Hensel Formation of South Texas. Clumped isotope paleothermometry of pedogenic carbonates result in temperature estimates between 35°C and 42°C. Clumped isotope paleothermometry of lake and palustrine carbonates from the Cedar Mountain Formation range from 15°C and 31°C for lake carbonates and 20°C to 44°C for palustrine carbonates. Farther north in Wyoming, we utilize the oxygen isotope value of semi aquatic taxa such as crocodilians and turtles to provide a proxy for water and utilize the oxygen isotope value of fish scales and teeth to estimate temperature at 26°C though with significant error. Preliminary clumped isotope paleothermometry provides a temperature of 25°C. The farthest north locality, the Kootenai Formation contains lacustrine, palustrine, and pedogenic carbonates. Utilizing a previous empirically-derived latitudinal gradient of meteoric water, carbonate d18O values were used to estimate a temperature range for the Kootenai between 13°C and 28°C. These values provide a temperature gradient for the Aptian-Albian over the mid latitudes of North America of ~-1°C/degree of latitude. 

Understanding of climate parameters and hydrology during past greenhouse conditions is important to forecasting future climate conditions. Oxygen isotopes of vertebrate bioapatites offer an opportunity to sample conditions across ancient landscapes. 112 samples from a variety of ecological niches were sampled from Cloverly Formation (Lower Cretaceous) micro-vertebrate site V1075 reposited at the Sam Nobel Museum at the University of Oklahoma. These samples were analyzed at the Keck Paleoenvironmental and Environmental Stable Isotope lab at the University of Kansas. Phosphate δ18O values range from between 9‰ to 23‰ vs. SMOW and show significant variability based on interpreted ecological niche of the taxa. Utilizing crocodilian and turtle d18Op values, environmental water oxygen isotope values are interpreted to be approximately -8‰ SMOW. These values are about 2-4‰ enriched relative to past estimates based on latitudinal gradients from penecontemporaneous formations from other latitudes. Based on water isotope estimates, fish δ18O values were used to calculate water temperature values of ~26°C which is consistent with estimated temperatures based on latitudinal gradients for the Cretaceous. In addition, preliminary carbonate clumped isotope paleothermometry suggest similar temperatures. These results along with emerging data from similar age deposits are beginning to build an emerging view of climate on the western side of the Western Interior Seaway during the late Early Cretaceous. 

Three extended abstracts are part of this special publication of Anatomical Record of the 14th Symposium on Mesozoic Terrestrial Ecosystems and Biota