Gryposaurus is based on specimen NMC 2278, a skull and partial skeleton collected in 1913 by George F. Sternberg from what is now known as the Dinosaur Park Formation of Alberta, along the Red Deer River.
As recently as 2007, the characterization of an unusual species of Gryposaurus, a duck-billed dinosaur, was announced.
The history of Kritosaurus took another turn in 1990, when Jack Horner and David B. Weishampel once again separated Gryposaurus, citing the uncertainty associated with the latter's partial skull.