Choristodera is an order of semi-aquatic diapsid reptiles that ranged from the Middle Jurassic, or possibly Late Triassic, to at least the early Miocene. It was named by Edward Drinker Cope in 1884. Choristoderes have been found in North America, Asia, and Europe. The most common fossils are typically found from the Late Cretaceous to the lower Eocene. Cladists have placed them between basal diapsids and basal archosauromorphs, but the phylogenetic position of Choristodera is still uncertain. It has also been proposed that they represent basal lepidosauromorphs. Most recently, workers have placed Choristodera within Archosauromorpha.