Acknowledgements

• The database analysed in this study is based on that assembled by T. Mike Keesey for his Dinosauricon web-site.

• David M. Martill commented extensively on a draft of the manuscript on which this presentation is based.

• I would never even have started this work without Mathew J. Wedel's encouragement; and it would have been much less useful without his criticism. He should make his mind up.

Notes: