The Jurassic landscape of 160 million years ago must have been a fearsome and unforgiving habitat with terrestrial tetrapods fearing such creatures as Dilophosaurus among other dramatic predators. The seas of that era contained a group of ferocious predators not yet popularised by movies or toys, or even in our common lexicon, but contemporaries of the dinosaurs—the ichthyosaurs. These creatures were highly successful and represent a dynasty of the Jurassic seas for perhaps 150 million years from 245–65 million years ago. Some of the larger of these ichthyosaurs could have had Dilophosaurus for lunch if the latter were foolhardy enough to enter the shallow seas.

Larger and longer than a London double decker bus, Temnodontosaurus or “cutting tooth lizard” successfully ruled the seas, red in tooth and fin, and was among the largest aquatic predators ever, perhaps with the exception Carcharodon megalodon, although the two probably never met.

To fill the niche of deeper water, however, these ichthyosaurs had to develop the visual resources to address these low light habitats. The visual imperative of feeding at 500–1000 metres or more, instead of the shallow seas of the continental shelf, would have required the development of large eyes with a surprising ability to …