A Megacerops.
Megacerops ('large-horned face', from méga- ‘large’ + kéras ‘horn’ + ōps ‘face’) is an extinct genus of the prehistoric odd-toed ungulate (hoofed mammal) family Brontotheriidae, an extinct group of rhinoceros-like browsers related to horses. It was endemic to North America during the Late Eocene epoch (38–33.9 mya), existing for approximately 4.1 million years.