Onager (weapon) Onager (weapon) The onager (British /ˈɒnədʒə/, /ˈɒnəɡə/, U.S. /ˈɑnədʒər/) was an imperial-era Roman torsion powered siege engine; in other words, a small catapult. The onager was first mentioned in 353 AD by Ammianus Marcellinus, who described onagers as the same as a scorpion. According to two authors of the later Roman Empire who wrote on military affairs, the onager derived its name from the kicking action of the machine that threw stones into the air, as did the hooves of the wild ass, the onager, which was native to the eastern part of the empire. The onager consisted of a
Onager seen feeding on seed pods such as "Prosopis" and breaking up woody vegetation with their hooves to get at more succulent herbs growing at the base of woody plants. During the winter, onagers also eat snow as a substitute for water. When natural water sources are unavailable, the onager digs holes in dry riverbeds to access subsurface water. The water holes dug by the onagers are often subsequently visited by domestic livestock, as well as other wild animals. Water is also found in the plants on which the onagers feed. During spring and summer in Mongolia, the succulent plants of