Palaeosyops is a genus of small brontothere which lived during the early to middle Eocene. It was about the size of large cattle, with a weight of 600–800 kg depending on the species.
Skull and reconstruction of P. leidyi
These animals are commonly found in Wyoming fossil beds primarily as fossilized teeth. From all of the species of this animal, it is concluded that P. major was the largest, reaching the size of a tapir. Its describer, Joseph Leidy, erroneously thought that Palaeosyops consumed both plants and animals after examining the fang-like canines. However, it is now known that all brontotheres were strict herbivores, and that many, if not most genera of hornless brontotheres had fang-like canines, possibly for both defense from predators, and intraspecific competition.