Sixty million years ago, the climate was warmer than it is today—from the equator to the poles. Dense, wet forests covered North America all the way to Alaska. How is it known that the climate was warmer? Many types of warm-climate plants, including palms, grew in places too cold for them now. This fossil palm leaf (Sabalites sp.), discovered in Petersburg Borough, Alaska, will be on display in “The David H. Koch Hall of Fossils—Deep Time,” opening June 8 at the Smithsonian’s National Museum of Natural History.
Credit: Lucia RM Martino, Smithsonian Institution