Equus simplicidens, also known as the Hagerman horse, lived around 4 million years ago in North America and is considered an ancestor of modern horses, zebras, and donkeys[3][5]. These animals relied on speed, stamina, and herd behavior for protection against predators such as early wolves and big cats[3]. Their survival was supported by strong social structures and collective awareness[3]. Over time, Equus species migrated to other continents via land bridges[4]. They eventually went extinct in North America around 10,000 years ago during the Pleistocene extinction event[1][2][4]. Horses were later reintroduced to the continent by humans in the late 15th century[4].

Citations: [1] POST-PLEISTOCENE HORSES (EQUUS) FROM MÉXICO https://meridian.allenpress.com/tjs/article/74/1/Article 5/487323/POST-PLEISTOCENE-HORSES-EQUUS-FROM-MEXICO [2] Horses in North America: A Comeback Story | Blog | Nature - PBS https://www.pbs.org/wnet/nature/blog/american-horses-horses-in-north-america-a-comeback-story/ [3] The Hagerman Horse (Equus simplicidens) - National Park Service https://www.nps.gov/articles/000/equus_simplicidens.htm [4] Wild Horses as Native North American Wildlife https://awionline.org/content/wild-horses-native-north-american-wildlife [5] Park Archives: Hagerman Fossil Beds National Monument https://npshistory.com/publications/hafo/index.htm [6] American Zebra (Equus simplicidens) - iNaturalist https://www.inaturalist.org/taxa/317782-Equus-simplicidens [7] Hagerman Horse - Start Packing Idaho https://www.startpackingidaho.com/blog/hagerman-horse/