A possible additional species from the Javelina Formation in Texas may extend the temporal range of the genus to 66 million years ago.

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.

This skull was missing the snout, which had eroded into fragments; Brown restored it after the duckbill now known as Edmontosaurus annectens, which was flat-headed,[4] and believed that some unusual pieces were evidence of compression.

[10] This hypothesis was most common in the late 1970s–early 1980s, and appears in some popular books;[11][12] one well-known work, The Illustrated Encyclopedia of Dinosaurs, uses Kritosaurus for the Canadian material (Gryposaurus), but identifies the mounted skeleton of K. incurvimanus as Hadrosaurus in a photo caption.

[14] Further research has revealed the presence of a second species, G. latidens, from slightly older rocks in Montana than the classic gryposaur localities of Alberta.

[16] New material from the Kaiparowits Formation of Utah, in Grand Staircase–Escalante National Monument, includes a skull and partial skeleton that represent the species G. monumentensis.

[25] G. latidens, from the late Santonian-early Campanian Lower Two Medicine Formation of Pondera County, Montana, USA, is known from partial skulls and skeletons from several individuals.

[33] This specimen also has the best example of skin impressions for Gryposaurus, showing this dinosaur to have had several different types of scalation: pyramidal, ridged, limpet-shaped scutes upwards of 3.8 centimeters long (1.5 inches) on the flank and tail; uniform polygonal scales on the neck and sides of the body; and pyramidal structures, flattened side-to-side, with fluted sides, longer than tall and found along the top of the back in a single midline row.

In profile view, they rise into a rounded hump in front of the eyes, reaching a height as tall as the highest point of the back of the skull.

[37] A subfamily, Gryposaurinae, was coined by Jack Horner as part of a larger revision that promoted Hadrosaurinae to family status,[16] but is not now in use.

[24] The paleontologists who unearthed G. monumentensis back in the 2000s brought the fact that this creature dined on tough, fibrous plant material which would imply that Gryposaurs was both a grazer and a browser.

[24] It could also have functioned as a tool for broadside pushing or butting in social contests, and there may have been inflatable air sacs flanking it for both visual and auditory signaling.

[16] Argon-argon radiometric dating indicates that the Kaiparowits Formation was deposited between 76.1 and 74.0 million years ago, during the Campanian stage of the Late Cretaceous period.

The plateau where dinosaurs lived was an ancient floodplain dominated by large channels and abundant wetland peat swamps, ponds and lakes, and was bordered by highlands.

[48] Gryposaurus monumentensis shared its paleoenvironment with other dinosaurs, such as dromaeosaurid theropods, the troodontid Talos sampsoni, ornithomimids like Ornithomimus velox, tyrannosaurids like Albertosaurus and Teratophoneus, armored ankylosaurids, the duckbilled hadrosaur Parasaurolophus cyrtocristatus, the ceratopsians Utahceratops gettyi, Nasutoceratops titusi and Kosmoceratops richardsoni and the oviraptorosaurian Hagryphus giganteus.

[49] Other paleofauna present in the Kaiparowits Formation included chondrichthyans (sharks and rays), frogs, salamanders, turtles, lizards and crocodilians.