Adelolophus ("unknown crest") is a genus of lambeosaurine hadrosaurid dinosaur (a crested "duck-bill") from Upper Cretaceous rocks in Utah, United States. It is based onUniversity of California Museum of Paleontology specimen 152028, a maxilla (tooth-bearing bone of the upper jaw). This specimen was found in the Campanian-age Wahweap Formation within Grand Staircase-Escalante National Monument. Adelolophus was described by Terry Gates and colleagues in 2014. The type and only known species is A. hutchisoni; the species name is a reference to Dr. Howard Hutchison, who found the specimen. The authors interpreted Adelolophus as the oldest known lambeosaurine from North America, at approximately 78 million years old.