Opthalmosaurus was a medium-sized Ichthyosaur of the Mid-Late Jurassic, 160-145 Million Years Ago. It was around 4.5-5.5 metres long and 1-2 tonnes in weight; nevertheless it was a speedy pursuit predator, often as with other Ichthyosaurus, anatomically compared to Dolphins and Marlin. Adults hunted in the deeper waters, whilst juveniles lingered in the coral reef systems until they were large enough to move into deeper water. Opthalmosaurus had evolved the largest eyes in proportion to body size or not, of any Vertebrate alive or extinct. Aptly, its name means, 'Eye lizard'.
Though far too large for any shark in its day, and a formiddable carnivore in its own right, Opthalmosaurus did live in the Jurassic Seas - so although we in the 21st Century would consider it relatively safe in the food chain if they still existed today, in the much more deadly Jurassic waters, it was a mere middling in a sea of even larger marine reptiles. Half eaten skeletons of Ichthyosaurs, some booth marks in bones, have been found in various Ichthyosaur genera. Some have been completely bitten in half, or decapitated. Opthalmosaurus would have been the target of massive Pliosaurs such as Liopleurodon.