Aublysodon (“backwards-flowing tooth") is a genus of carnivorous dinosaurs known only from the Judith River Formation in Montana, which has been dated to the late Campanian age of the late Cretaceous period (about 75 million years ago). The only currently recognized species, Aublysodon mirandus, was named by paleontologist Joseph Leidy in 1868. It is now considered dubious, because the type specimen consists only of an isolated premaxillary (front) tooth. Although this specimen is now lost, similar teeth have been found in many US states, western Canada, and Asia. These teeth almost certainly belong to juvenile tyrannosaurine tyrannosaurids, but most have not been identified to species level. However, it is likely that the type tooth (and therefore the name Aublysodon mirandus itself) belongs to one of the species in the genus Daspletosaurus, which was present in contemporary formations, and which matches specific details of the original tooth. The synapomorphies alleged to distinguish the Aublysodontinae, especially lack of serrations on premaxillary teeth could have been caused by tooth wear in life, postmortem abrasion, or digestion. Most other "aublysodontine"-type teeth may be from ontogenetic stages or sexual morphs of other tyrannosaurids. Apart from the type species Aublysodon mirandus over the years several other species have been named. These are now all considered either dubious or identical to other species or as having no close connection to A. mirandus. History In the mid-to-late 19th century many dinosaur taxa were named for isolated teeth; such genera include Trachodon, Palaeoscincus, and Troodon. Even before the badlands of North America started revealing the bones of Tyrannosaurus, teeth turning up in many localities in the Western United States revealed the presence of large predatory dinosaurs. In 1856 Joseph Leidy had named fourteen teeth collected by Ferdinand Vandeveer Hayden in 1854 and 1855 from the Judith River Badlands of Montana as the species Deinodon horridus. In 1866 Edward Drinker Cope chose three nonserrated teeth from the original syntype series of fourteen as the lectotypes of Deinodon horridus. Leidy named these same three teeth Aublysodon mirandus in 1868. The meaning of the generic name is uncertain because Leidy himself gave no etymology or explanation of the intended meaning. It is possible the genus name is derived from Greek αὖ, au, "again", "backwards", "contrariwise", βλύζω, blyzo, "to spout", "to flow" and ὀδών, odon, "tooth". The specific name means "wonderful" or "strange" in Latin. Because the name Aublysodon mirandus was based on