I want to know the answer to the following question:
What may have replaced the "hind wing" as the primary mode of aerial maneuverability?
All the background I'm provided with is that "The later included the superficially gull-like Ichthyornis, the Hesperornithiformes, which became so well adapted to hunting fish in marine environments that they lost the ability to fly and became primarily aquatic.". Is that enough to answer the question?