ACKNOWLEDGEMENTS

This work was possible through the generous support of the Swiss National Foundation (grant no. 20-5305.87, and grant no. 2000-043058.95/1 for computer equipment applied for completion of this investigation). I thank Hans Thierstein for his interest, enthusiasm and discussions during data collection and analysis. Thanks go also to Dave Lazarus and Scott Hills, who helped analyzing and interpreting the data during a very early phase of this investigation, to Norman MacLeod and three reviewers for constructive comments and improvement of the English language. I acknowledge the support of the Natural History Museum and the City of Basel to bring this investigation to an end.