's initial flatheaded reconstruction of the skull of
K. navajovius, 1910 In 1904,
Barnum Brown discovered the
type specimen (
AMNH 5799) of
Kritosaurus near the
Ojo Alamo Formation,
San Juan County,
New Mexico,
United States, while following up on a previous expedition. He initially could not definitely correlate the
stratigraphy, but by 1916 was able to establish it as from what is now known as the
late Campanian-age De-na-zin Member of the
Kirtland Formation. When discovered, much of the front of the skull had either eroded or fragmented, and Brown reconstructed this portion after what is now called
Edmontosaurus, leaving out many fragments. He initially wanted to name it
Nectosaurus, but found out that this name was already in use;
Jan Versluys, who had visited Brown before the change, inadvertently leaked the previous choice. He kept the specific name, though, leading to the combination
K. navajovius. The 1914 publication of the arch-snouted Canadian genus
Gryposaurus changed Brown's mind about the anatomy of his dinosaur's snout. Going back through the fragments, he revised the previous reconstruction and gave it a
Gryposaurus-like arched
nasal crest. a move supported by
Charles Gilmore. now considered a synonym of
Gryposaurus notabilis) and became standard after the publication of
Richard Swann Lull and
Nelda Wright's 1942
monograph on North American hadrosaurids. From this time until 1990,
Kritosaurus would be composed of at least the
type species K. navajovius,
K. incurvimanus, and
K. notabilis, the former type species of
Gryposaurus. The poorly known species
Hadrosaurus breviceps (
Marsh, 1889), known from a
dentary from the Campanian-age
Judith River Formation of
Montana, was also assigned to
Kritosaurus by Lull and Wright, By the late 1970s and early 1980s,
Hadrosaurus had entered the discussion as a possible synonym of either
Kritosaurus,
Gryposaurus, or both, particularly in semi-technical "dinosaur dictionaries".
David B. Norman's
The Illustrated Encyclopedia of Dinosaurs, uses
Kritosaurus for the Canadian material (
Gryposaurus), but identifies the mounted skeleton of
K. incurvimanus as
Hadrosaurus. The synonymization of
Kritosaurus and
Gryposaurus that lasted from the 1910s to 1990 led to a distorted picture of what the original
Kritosaurus material represented. Because the Canadian material was much more complete, most representations and discussions of
Kritosaurus from the 1920s to 1990 are actually more applicable to
Gryposaurus. This includes, for example, James Hopson's discussion of hadrosaur cranial ornamentation,
Formerly assigned species and material In 1984,
Argentine paleontologist José Bonaparte and colleagues named
Kritosaurus australis for hadrosaur bones from the late Campanian-
early Maastrichtian Los Alamitos Formation of
Rio Negro,
Patagonia,
Argentina. In 2010, this species was thought to be a synonym of
Secernosaurus koerneri. Further analysis proved the bones to belong to a new genus. Thus,
Huallasaurus was named by Rozadilla
et al. (2022). In 1990,
Jack Horner and
David B. Weishampel once again separated
Gryposaurus, citing the uncertainty associated with the latter's partial skull. Horner in 1992 described two more skulls from New Mexico that he claimed belonged to
Kritosaurus and showed that it was quite different from
Gryposaurus,
Adrian Hunt and
Spencer G. Lucas,
American paleontologists, named
Anasazisaurus horneri in 1993. The name was derived from the
Anasazi, an ancient
Native American people, and the
Greek word
sauros ("lizard"). The Anasazi were famous for their
cliff-dwellings, such as those in
Chaco Canyon, near the location of
fossil Anasazisaurus remains. The term "Anasazi" itself is actually a
Navajo language word,
anaasází ("enemy ancestors"). The species was named in honor of
Jack Horner, the American paleontologist who first described the skull in 1992. The
holotype skull (and only known specimen) was collected in the late 1970s by a
Brigham Young University field party working in
San Juan County, and is housed at BYU as BYU 12950. Horner originally assigned the
Anasazisaurus skull to
Kritosaurus navajovius, A comprehensive study of known
Kritosaurus material published by Albert Prieto-Márquez in 2013 upheld the status of
Naashoibitosaurus as a distinct genus, but found that the type specimens of
Kritosaurus and
Anasazisaurus were indistinguishable when comparing overlapping elements (i.e. only those bones preserved in both specimens). Prieto-Márquez therefore regarded
Anasazisaurus as a synonym of
Kritosaurus, but retained it as the distinct species
K. horneri. A partial skeleton from the Sabinas Basin in Mexico was described as
Kritosaurus sp. by Jim Kirkland and colleagues,
Kritosaurus fossils have also been unearthed in the
Olmos Formation in Mexico. ==Description==