Naashoibitosaurus
From Navajo naʼashǫ́ʼii bitooh, meaning 'creek lizard'; named after the Naashoibito Member of the Kirtland Formation where the specimen was thought to have been found
Naashoibitosaurus is a genus of hadrosaurid dinosaur that lived about 73 million years ago, in the Late Cretaceous, and was found in the Kirtland Formation of the San Juan Basin in New Mexico, United States. Only a partial skeleton has been found to date. It was first described as a specimen of Kritosaurus by Jack Horner, and has been intertwined with the taxon since its description.
Under dispute
Naashoibitosaurus ostromi has been treated as a junior synonym of Kritosaurus navajovius (Prieto-Márquez, 2010), and Lehman and colleagues (2016) took its similarity to K. navajovius as support for synonymy, but Prieto-Márquez (2013) recovered it as a valid kritosaurin, distinct from Kritosaurus in characters of the maxilla, jugal, prefrontal, quadrate, frontal and infratemporal fenestra. Dalman and colleagues (2025) recovered it as sister to Ahshislesaurus in a southern Laramidian clade they treat as separate from Kritosaurini. It is placed at Saurolophinae.
Diagnosis
- Nasal arch rises above anterior end of orbits, distinguishing from other hadrosaurids except Gryposaurus
- Nasals bifurcate posteriorly with frontals extending anteriorly between nasals along midline, differs from Gryposaurus
- Posterior processes of nasals overlapped by extensive medial prefrontal wings so nasal transverse width narrower than prefrontal width in dorsal view
Species
Naashoibitosaurus ostromi Hunt & Lucas, 1993 Disputed
Type species
Named in honor of John Ostrom.
- Holotype
- NMMNH P-16106 , New Mexico Museum of Natural History and Science
- Material
- Partial skull including skull roof, and associated postcrania
- Horizon
- De-na-zin Member, Kirtland Formation, Campanian, Late Cretaceous , 83.6–72.2 million years ago
- Locality
- New Mexico, United States
References
- Hunt, A. P.; Lucas, S. G. (1993). Cretaceous vertebrates of New Mexico. New Mexico Museum of Natural History and Science Bulletin 2: 77-91. hunt1993a
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Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Ornithischians. Princeton University Press.
Source of the body length estimate.
jones2026a -
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
Recovered Naashoibitosaurus as a valid kritosaurin.
prieto-márquez2013c -
Prieto-Márquez, A. (2010). Global phylogeny of Hadrosauridae (Dinosauria: Ornithopoda) using parsimony and Bayesian methods. Zoological Journal of the Linnean Society 159(2): 435-502. Oxford University Press (OUP). doi:10.1111/j.1096-3642.2009.00617.x
Referred NMMNH P-16106 to Kritosaurus navajovius.
prieto-márquez2010c - Sullivan, R. M. (1999). Nodocephalosaurus kirtlandensis, gen. et sp. nov., a new ankylosaurid dinosaur (Ornithischia: Ankylosauria) from the Upper Cretaceous Kirtland Formation (upper Campanian), San Juan Basin, New Mexico. Journal of Vertebrate Paleontology 19(1): 126-139. Informa UK Limited. doi:10.1080/02724634.1999.10011128 sullivan1999a
- Dalman, S. G.; Jasinski, S. E.; Malinzak, D. E.; Lucas, S. G.; Kundrát, M.; Fiorillo, A. R. (2025). A new saurolophine hadrosaurid (Ornithischia: Hadrosauridae) from the Upper Cretaceous (Campanian) Hunter Wash Member, Kirtland Formation, San Juan Basin, New Mexico. Fossil Record 11 101: 73-114. New Mexico Museum of Natural History and Science. dalman2025a
- Lehman, T. M.; Wick, S. L.; Wagner, J. R. (2016). Hadrosaurian dinosaurs from the Maastrichtian Javelina Formation, Big Bend National Park, Texas. Journal of Paleontology 90(2): 333-356. Cambridge University Press. doi:10.1017/jpa.2016.48 lehman2016a