Paper No. 14
Presentation Time: 4:45 PM


CARVALHO, Mónica R., Department of Plant Biology, Cornell University, Ithaca, NY 14853, LONDOÑO, Liliana, Center for Tropical Paleoecology and Archaeology, Smithsonian Tropical Research Institute, Balboa, Ancon, 0843-03092, Panama, WOOD, Aaron, Florida Museum of Natural History, University of Florida, Dickinson Hall, Gainesville, FL 32611-7800, CÁRDENAS, Andrés L., Universidad EAFIT, Departamento Ciencias de la Tierra, Carrera 49 N. 7 Sur -50, Medellin, Colombia, ESCOBAR, Jaime H., Department of Civil and Environmental Engineering, Universidad del Norte, Apartados Aereos 1569, Barranquilla, 51820, Colombia, HERRERA, Fabiany, Florida Museum of Natural History & Biology Department, University of Florida, Museum Rd and Newell Dr, Dickinson Hall, Gainesville, FL 32611-7800, JARAMILLO, Carlos, Smithsonian Tropical Research Institute, Unit 0948, APO AA 34002, Balboa, Ancon, 0843-03092, Panama and ROYER, Dana L., Department of Earth and Environmental Sciences, Wesleyan University, Middletown, CT 06459,

The preservation of leaf organic remains and cellular details provide a unique framework for interpreting past climates and environments based on isotopic signatures and core physiological processes that are heavily influenced by morphology. The middle Miocene climatic optimum (MMCO, 15-17 Ma) is one of the best analogues to our ongoing global warming as it occurred during the long-term global climatic cooling trend we have had for the past 20 Ma. Any paleobiological data retrieved from this time period is thus valuable for understanding current climatic perturbations. We report the recent discovery of an outstandingly preserved middle Miocene leaf assemblage from the Pedro-Miguel Formation, in the basin of the Panamá Canal. This leaf assemblage comprises at least fifteen morphotypes of (nearly) whole-leaf cuticles, some of which have been assigned to typical Neotropical families including Fabaceae, Anacardiaceae and Moraceae. We interpret that the rapid burial of the forest litter in relation to surrounding volcanic activity favored the preservation of intact cuticles and cellular details in these leaves, and provides a unique opportunity to combine leaf anatomical and biochemical data for inferring past forest ecology. The visualization of species-specific stomatal pore, epidermal and mesophyll cell size, in addition to carbon isotopic signatures can be used to infer primary leaf physiological traits such as water use efficiency, mesophyll conductance, and estimate CO2 levels during the Middle Miocene Climatic Optimum from this Neotropical setting.