The Allotrioceratidae is a family of Middle Ordovician fossils, established by Rousseau Flower, 1955, originally including Allotrioceras and Mirabilocras, assigned inferentially to the Endocerida and known only from structures interpreted as siphuncles. Later Williamsoceras, Cacheoceras, and Perkinsoceras (Flower 1968, 1976) were added. The holotypes of Allotrioceras and Mirabiloceras are housed in the collections of the New Mexico Museum of Natural History and Science in Albuquerque, New Mexico.