Hesperornis ('western bird') was a diving bird, similar to extant cormorants. Unlike those, it was surprisingly large, up to 1.8 metres (5.9 ft) long, and had only very small wings. It had both teeth and a beak. The discovery of Hesperornis in the late 19th century was an important find, which helped solidify the theory of the evolutionary link between birds and reptiles.

(Cretaceous, 83.5-78 million years ago)