1933, short for ornithopod dinosaur (1888), from Modern Latin Ornithopoda (1881), the suborder of dinosaurs whose hind legs are like those of birds, from ornitho- "bird" + Greek podos, genitive of pous "foot" (from PIE root *ped- "foot").
ornitho-
ornithological
ornithologist
ornithology
ornithomancy
ornithopod
ornithopter
oro-
orogeny
orotund
orphan