Mosasaurs were large, flipper-bearing swimming lizards from the age of the last dinosaurs, about 100–66 million years ago. Typically reaching the size of a pickup truck in length—and some nearly twice as long—over 70 mosasaur species are reported today based on the fossils collected from all over the world. Out of this highly diverse assemblage, halisaurine mosasaurs were small and seemed less well adapted to life in water since they lacked the well-developed flippers and tail fin of their larger contemporaries. Yet these small mosasaurs became increasingly more common in the fossil record towards the end of the Cretaceous, indicating their evolutionary success alongside their larger, fast-swimming cousins.
In his talk, Dr. Takuya Konishi, from the University of Cincinnati, explains why a recently discovered skull from Japan sheds new light on halisaurine mosasaurs’ potential survival strategy: that halisaurines evolved a pair of large, forward-facing eyes that would have increased their ability to see in the dark, allowing them to hunt at night.