The Hesperocyon fact pages online are sparse, but there are some. Thankfully, Bob Strauss is highly regular in covering vastly different types of fossil creatures. Therefore, as usual, About has a fairly good fact page dedicated to Hesperocyon. The Department of Mineral Resource of North Dakota has also put together a rather short but nice series of pdfs on the fossil creatures that have been recovered from the soils and rocks of North Dakota. One, of course, is the rather adorable looking Hesperocyon shown here. The page includes maps of the counties in which the fossil has been discovered as well. Additionally, there is a link to a map of other fossil vertebrates discovered in North Dakota on the pdf fact page that is very interesting and well illustrated.