ACKNOWLEDGMENTS
The authors thank S. Chapman (NHMUK), H. Furrer (PIMUZ), R. Schoch (SMNS) and G. Wass (PETMG) for providing access to collections, J. Hurum and E. Knutsen (PMO), and M. Caldwell for logistical support. The authors also thank A. Leblanc and M. Caldwell for discussion. This research was supported by an I. W. Killam Memorial Postdoctoral Fellowship to E.M., and a Sir Mark Mitchell Research Foundation Grant to M.Z. Photos of Ichthyosaurus and Ophthalmosaurus by E.M.; NHMUK and PETMG retain copyright of the raw images.
Handling editor: F. Robin O’Keefe