Canid diversity for each of the subfamilies: Hesperocyoninae (brown), Borophaginae (purple), and Caninae (green).  The two extinct subfamilies, Hesperocyoninae and Borophaginae, achieved their maximum diversity in 28 Ma and 14 Ma respectively.  Whereas the subfamily Caninae did not diversify until much later during the Pliocene and Pleistocene (5 Ma and later).  The width of the horizontal bars represents the number of species in a slice of time.  Scales on the left are ages in million years and the North America Land Mammal Ages.