1. Department of Palaeobiology, Swedish Museum of Natural History, Stockholm, Sweden
2. Bolin Centre for Climate Research, Stockholm University, Stockholm, Sweden
3. School of Agriculture and Food Science, University College Dublin, Dublin 4, Ireland
4. Department of Biology, University of Fribourg, Fribourg, Switzerland
5. Botany Department, School of Natural Sciences, Trinity College Dublin, the University of Dublin, Dublin 2, Ireland