Diclonius

Diclonius (meaning "double sprout") is a genus of dinosaur from the Late Cretaceous. It was a hadrosaur based solely on teeth. Its fossils were found in the Judith River Formation of Montana, northern US. The name is in reference to the method of tooth replacement, in which newly erupting replacement teeth could be in functional use at the same time as older, more worn teeth. Thus, the number of "sprouting" teeth was doubled in comparison to Monoclonius ("single sprout"), which used only one set of teeth at a time and which Cope named in the same paper.

The type species, Diclonius pentagonus, was named by Edward Drinker Cope in 1876, based on a single tooth specimen (AMNH 3972). Other formally undescribed species include D. calamarius and D. perangulatus. Although Cope referred several other batches of teeth to the genus, under several species, the name is considered a nomen dubium.