Morphometric comparison of the Hesperornithiformes and modern diving birds

The Cretaceous Hesperornithiformes are an extinct group of aquatic birds long recognized to have practiced foot-propelled diving. This specialization is seen today in a number of modern avian families (loons, grebes, cormorants, and some ducks) that have convergently derived a diving lifestyle. Historically, hesperornithiforms have usually been compared to modern loons and grebes as analogues. However, these comparisons are based on qualitative...