The loons were often considered to be the most ancient of the northern hemisphere bird families because of a similarity with the actually entirely unrelated extinct Cretaceous Order Hesperornithiforms. Now they are considered more modern and Anseriformes (waterfowl) and Galliformes (chicken-like) are the most ancient.

The Common Loon,  Gavia immer is known as the Great Northern Diver in Eurasia.  They are mainly Nearctic and where their breeding habitat may be from wooded lakes to tundra ponds.  North American birds migrate during the day, and winter along the Atlantic and Pacific coasts, while many stop off at the Great Lakes. They dive up to 200′ and feed mainly on fish supplemented with Arthropods, such as crayfish, also snails, worms, and aquatic vegetation.