ACKNOWLEDGEMENTS

For access to the Sphenodon skull (specimen LDUCZ x036) we thank J. Ashby, M. Carnall, and N. McEnroe (Grant Museum of Zoology, UCL, UK), and for the micro-CT dataset (specimen YPM9194), we thank L.K. Murray and C.J. Bell (University of Texas, Austin, USA). For her general help and in this instance the scanning of specimen LDUCZ x036 we thank S. Taft at the University of Hull, UK. We also gratefully acknowledge the Biotechnology and Biological Sciences Research Council (BBSRC - grants BB/E007465/1, BB/E009204/1 and BB/E007813/1) who funded this research.