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Kritosaurus

Brown, 1910 KRIT-o-SAWR-us

From Greek kritos (separated) and sauros (lizard); meaning "separated lizard", referring to the arrangement of the cheek bones in the type skull

83.6–72.2 million years ago Campanian, Late Cretaceous
Late Cretaceous stages

Kritosaurus is an incompletely known genus of hadrosaurid (duck-billed) dinosaur. It lived about 74.5-66 million years ago, in the Late Cretaceous of North America. The name means "separated lizard" (referring to the arrangement of the cheek bones in an incomplete type skull), but is often mistranslated as "noble lizard" in reference to the presumed "Roman nose" (in the original specimen, the nasal region was fragmented and disarticulated, and was originally restored flat).

Diagnosis

  1. Dorsolateral margin of the maxilla (rostral and adjacent to the jugal articular surface) 40% or more of the distance between the rostral end of the maxilla and the caudoventral corner of the jugal's orbital margin (autapomorphy).
  2. Jugal with the orbital constriction deeper than the infratemporal constriction.
  3. Infratemporal fenestra larger than the orbit, with its dorsal margin greatly elevated above the dorsal orbital margin in adults (postorbital squamosal ramus forming more than a 20° angle with the maxillary tooth row).
  4. Frontal participating in the orbital margin via an intervening apex between the prefrontal and postorbital (convergent in Brachylophosaurini).
  5. Paired caudal parasagittal processes of the nasals resting over the frontals, with the rostromedial margin of the frontals inserting between the nasal processes.

Species

Kritosaurus navajovius Brown, 1910

Type species

Named for the Navajo people and their territory in the American Southwest, where the type specimen was collected in San Juan County, New Mexico.

Holotype
AMNH 5799 , American Museum of Natural History
Material
Incomplete skull: partial predentary, nearly complete dentaries, partial surangulars, right splenial/angular/articular, fragmentary premaxillae, caudal nasals, partial maxillae and jugals, right quadratojugal, partial quadrates, prefrontals, postorbitals, and squamosals, frontals, a nearly complete parietal, braincase elements, the palatal complex, and the atlas.
Horizon
De-na-zin Member, Kirtland Formation, Campanian, Late Cretaceous , 83.6–72.2 million years ago
Locality
west of Chaco Canyon, Ojo Alamo, New Mexico, United States

Synonyms of the genus

Name Type Reason
Nectosaurus preoccupied Name preoccupied by Nectosaurus (Reptilia).

References

  1. Brown, B. (1910). The Cretaceous Ojo Alamo beds of New Mexico with description of the new dinosaur genus Kritosaurus. Bulletin of the American Museum of Natural History 28(24): 267-274. brown1910a
  2. Prieto-Márquez, A. (2013). Skeletal morphology of Kritosaurus navajovius (Dinosauria: Hadrosauridae) from the Late Cretaceous of the North American south-west, with an evaluation of the phylogenetic systematics and biogeography of Kritosaurini. Journal of Systematic Palaeontology 12(2): 133-175. Informa UK Limited. doi:10.1080/14772019.2013.770417

    Detailed redescription and rediagnosis of the holotype AMNH 5799; places Kritosaurus within Kritosaurini and proposes Anasazisaurus as a junior synonym.

    prieto-márquez2013c