University of Oregon

Department of Paleobiology, National Museum of Natural History, Smithsonian Institution

Professor of Earth and Environmental Sciences, Wesleyan University

Universidad de Murcia

Emeritus Professor of Earth Sciences, The Open University, UK

Department of Paleobiology, National Museum of Natural History, Smithsonian Institution

Chair for Botany: Functional Morphology and Biomimetics, University of Freiburg

Curator of Paleobotany, Florida Museum of Natural History, University of Florida

School of Biological Sciences, The University of Adelaide

Professor, Pennsylvania State University, Department of Geosciences