1. Department of Paleobotany and Paleoecology, Cleveland Museum of Natural History1 Wade Oval Dr., Cleveland, OH 44106, USA
2. Department of Paleobiology, National Museum of Natural History, Smithsonian Institution10th St. & Constitution Ave. NW, Washington, DC 20013, USA
3. Department of Geological Sciences, Stanford University450 Jane Stanford Way, Building 320, Stanford, CA 94305, USA