1. Chicago Botanic Garden Glencoe Illinois 60022 USA
2. State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology and Center for Excellence in Life and Paleoenvironment Chinese Academy of Sciences Nanjing 210008 China
3. Institute of Paleontology, Mongolian Academy of Sciences Ulaanbaatar–15160 Mongolia
4. Department of Geological Sciences Stanford University California 94305 USA
5. Oak Spring Garden Foundation, Oak Spring, Upperville Virginia 20184 USA
6. Yale School of the Environment Yale University New Haven Connecticut 06511 USA