Much work has been done on the study of vertebrate gaits over the pastseveral decades and efforts undertaken to apply this to fossil tracks,especially dinosaurs and mammals such as cats, dogs, camels, and horses.This work seeks to expand upon such studies and in particular to studyfootprints laid down in sand by modern horses and apply such studies todetermine the gaits of fossil horse trackways. It thus builds upon the workof Renders (1984a, b) and Kienapfel et al. (2014) and suggests additionalmeasurements that can be taken on horse footprints. In this study thefootprints left in the sand by 15 horses of various breeds with variousgaits were videotaped, photographed, described, and measured in order todetermine characteristics useful in distinguishing gaits. These results werethen applied to two new sets of fossil footprints, those of the middleMiocene merychippine horse Scaphohippus intermontanus that I personally examined and measured andthose from the late Pleistocene horse Equus conversidens, previously illustrated and describedin the literature (McNeil et al., 2007). The latter horse exhibits a fastgallop of around 9.4 m/s, but it is the former whose footprints are quiteunique. The quantitative and visual features of these prints are suggestiveof a medium-fast gait involving apparent “understepping” of diagonalcouplets and hind feet that overlap the centerline. The gait that mostclosely matches the footprints of Scaphohippus is the “artificial” gait of a slowrack or tölt, or pace, around 1.9 m/s, though an atypical trot of a horsewith major conformation issues or which is weaving (swaying) from side toside is a less likely possibility. This intimates, along with the earlierstudy of Renders (1984a, b), who found the artificial gait of the running walkdisplayed by Pliocene hipparionine horses, that ancient horses possessed amuch greater variety of gaits than modern horses and that over time theylost these abilities with the exception of certain gaited breeds.