Nodocephalosaurus

Nodocephalosaurus is a genus of herbivorous ankylosaurine ankylosaurid dinosaur from Upper Cretaceous (late Campanian stage) deposits of San Juan Basin, New Mexico. The holotype, SMP VP-900, was recovered from the Late Campanian De-na-zin Member of the Kirtland Formation and consists of an incomplete skull. Nodocephalosaurus (Greek nodus = knob, kephale = head and sauros = lizard) is a monotypic genus, including only the type species, Nodocephalosaurus kirtlandensis. Dinosaurs like Nodocephalosaurus resembled Asian forms, and may be evidence for Asian dinosaurs migrating to North America in the Late Cretaceous.[1]

Nodocephalosaurus
Temporal range: Late Cretaceous, Campanian
Nodocephalosaurus holotype SMP VP-900 skull on the right
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Order: †Ornithischia
Family: †Ankylosauridae
Subfamily: †Ankylosaurinae
Genus: †Nodocephalosaurus
Sullivan, 1999
Type species
†Nodocephalosaurus kirtlandensis
Sullivan, 1999

Description and classification
Skull (upper right), compared to other ankylosaurids

The pattern of cranial ornamentation present in this ankylosaurid "is distinguished by semi-inflated to bulbous, polygonal, cranial osteoderms that are bilaterally and symmetrically arranged on the frontonasal region of the skull",[2] and includes deltoid quadratojugal flanges and pyramid-shaped squamosal bosses. Paul estimated its length at 4.5 meters (15 ft) and its weight at 1.5 tonnes (1.65 short tons).[3]

The type description noted the taxon's similarity to the Mongolian ankylosaurids Saichania chulsanensis and Tarchia gigantea, and suggested that these three taxa form a clade within the subfamily Ankylosaurinae. However, Vickaryous and others consider this assignment provisional and list the genus as Ankylosaurinae incertae sedis.[4]

There is also evidence of a paranasal sinus cavity in the maxilla. Sullivan also noted that material previously collected from the Kirtland Formation and assigned to the taxa Euoplocephalus or Panoplosaurus might actually represent additional remains of Nodocephalosaurus.[2] By way of comparison, the head armor of Nodocephalosaurus is strikingly similar to that of Akainacephalus, a related form discovered in the Kaiparowits Formation in 2018.[5]

See also

References
  1. Lehman, T.M. (2001). Tanke, D.H.; Carpenter, K. (eds.). "Late Cretaceous dinosaur provinciality". Mesozoic Vertebrate Life. Indiana University Press. 310: 321.
  2. Sullivan, R. (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. doi:10.1080/02724634.1999.10011128.
  3. Paul, Gregory S. (2010). The Princeton Field Guide to Dinosaurs. New Jersey: Princeton University Press. pp. 232–233.
  4. Weishampel, D.B.; Dodson, P.; Osmólska, H., eds. (2004). "Chapter 17: Ankylosauria". The Dinosauria (2nd ed.). University of California Press. ISBN 9780520941434.
  5. Wiersma, J.P.; Irmis, R.B. (2018). "A new southern Laramidian ankylosaurid, Akainacephalus johnsoni gen. et sp. nov., from the upper Campanian Kaiparowits Formation of southern Utah, USA". PeerJ. 6: e5016. doi:10.7717/peerj.5016. PMC 6063217. PMID 30065856.
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