1. Department of Earth and Environmental Sciences Wesleyan University Middletown 06459 CT USA
2. State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology Chinese Academy of Sciences Nanjing 210008 China
3. Institute of Paleontology Mongolian Academy of Sciences Ulaanbaatar 15160 Mongolia
4. Chicago Botanic Garden Chicago 60022 IL USA
5. Oak Spring Garden Foundation, Oak Spring Upperville 20184 VA USA
6. Yale School of Environment Yale University New Haven 06511 CT USA
7. Earth Sciences, Negaunee Integrative Research Center Field Museum Chicago 60605 IL USA