A well-preserved flora has been collected from the Upper Cretaceous Blackhawk Formation near Salina, Utah. This formation is part of the Mesaverde Group and consists mostly of deltaic sediments deposited along the western margin of a Cretaceous sea. The Blackhawk Flora is comprised of the following species: Eguisetum sp., Osmunda hollickii, Allantodiopsis erosa, Saccoloma gardneri, Araucaria longifolia, Ginkgo laramiensis, Protophyllocladus polymorphus, Sequoia affinis, Geonomites imperialis, Sabalites montanus, Dryophyllum subfalcatum, Juglans similis, Cinnamomum sezannense, Magnolia ampifolia, Menispermum dauricumoides, Ficus glasconea, Ficus planicostata, Ficus puryearensis var. elongata, Myrtophyllum torreyi, Nymphaeites dawsonii, Dalbergia (?) prewilcoxiana, Salix lesquereuxii, and Trapa paulula. Two independent studies were used to determine the climatic conditions that existed when the Blackhawk Flora was living. The first study was an analysis of the fossil leaf features compared with features of modern leaves whose climatic requirements are known. It was determined that the fossil leaves of the woody dicotyledonous species exhibit a high percentage of entire margins, pinnate venation, simple organization, thick texture, large size, and dripping points. These are characters possessed by modern floras living in warm, humid climates. The second study was of the distribution of the nearest living relatives of the fossil plants. This investigation indicated that the modern correlatives of the Blackhawk Flora prefers climates that are warm-temperate to subtropical. Both paleoclimatic studies indicate that the Blackhawk Flora lived in a humid, warm-temperate to subtropical climate.

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