Open Paleo

Nedoceratops

Hatcher, 1905 ned-o-SEH-ruh-tops Disputed

From Russian 'nedo' (insufficient) and Greek 'keratops' (horned face); meaning 'insufficient horned face', in reference to the absence of a prominent nasal horn on the holotype skull.

72.2–66.0 million years ago Maastrichtian, Late Cretaceous
Late Cretaceous stages

Nedoceratops is a controversial genus of ceratopsid dinosaur from the Late Cretaceous period Lance Formation of North America. It is known only from a single skull discovered in Wyoming. Its status is the subject of ongoing debate among paleontologists: some authors consider Nedoceratops a valid, distinct taxon, while others consider it to be an unusual specimen of Triceratops.

Under dispute

The validity of Nedoceratops is actively contested. Scannella and Horner (2010) treated USNM 2412 as a transitional growth stage of Triceratops. Farke (2011) disagreed, tentatively treating Nedoceratops as a distinct chasmosaurine genus diagnosed by an undifferentiated nasal horncore, near-vertical postorbital horncores, and small parietal fenestrae. Scannella and Horner (2011) replied, maintaining that the Triceratops, Torosaurus and Nedoceratops morphologies are growth stages of a single genus, Triceratops. Maiorino and colleagues (2013) found its morphometric affinities equivocal, with the squamosal and frill within Triceratops morphospace though overall skull shape is ambiguous. No broad consensus has been reached.

Diagnosis

  1. Nasal horncore nearly completely undifferentiated from the nasal bone, appearing as a poorly defined swelling rather than a discrete horn or knob.
  2. Greater portion of the procurved postorbital horncores forms approximately a 90-degree angle with the tooth row.
  3. Parietal fenestrae extremely small, occupying less than five percent of the total surface area of the parietal.
  4. Ventral extremity of the squamosal positioned well above the alveolar process of the maxilla.

Species

Nedoceratops hatcheri Hatcher, 1905 Disputed

Type species

Honors John Bell Hatcher, who collected the holotype skull in 1891; the original combination Diceratops hatcheri was published by Lull (1905) from Hatcher's posthumous description.

Holotype
USNM 2412 , National Museum of Natural History, Smithsonian Institution
Material
Nearly complete cranium approximately 1.8 m in greatest length; lacks the caudal margin of the parietal and most of the right postorbital horncore. Nearly all cranial sutures are obliterated by co-ossification, indicating an old adult individual.
Horizon
Lance Formation, Maastrichtian, Late Cretaceous , 72.2–66.0 million years ago
Locality
about three miles southwest of the mouth of Lightning Creek, Wyoming, United States

Synonyms of the genus

Name Type Reason
Diceratops preoccupied Original generic combination, preoccupied by Diceratops Förster, 1869 (a hymenopteran wasp in Ichneumonidae). The dinosaur was renamed Nedoceratops by Ukrainsky (2007).
Diceratus junior objective Independent replacement name proposed by Mateus (2008) for the preoccupied Diceratops Lull, 1905, but Ukrainsky (2007) had already published Nedoceratops with priority. Diceratus is therefore an unused junior objective synonym of Nedoceratops.

References

  1. Hatcher, J. B. (1905). Two new Ceratopsia from the Laramie of Converse County, Wyoming. American Journal of Science 20(120): 413-419. doi:10.2475/ajs.s4-20.120.413

    Erects Diceratops hatcheri (= Nedoceratops) on skull USNM 2412; the name is Lull's (published posthumously, 1905, from Hatcher's manuscript). Later renamed Nedoceratops by Ukrainsky (2007).

    hatcher1905a
  2. Lull, R. S. (1905). Restoration of the horned dinosaur Diceratops. American Journal of Science 20(120): 420-422. doi:10.2475/ajs.s4-20.120.420

    Lull's companion Restoration of the horned dinosaur Diceratops; interpreted it as distinct from Torosaurus but closely allied to Triceratops in the same lineage.

    lull1905a
  3. Ukrainsky, A. S. (2007). A new replacement name for Diceratops Lull, 1905 (Reptilia: Ornithischia: Ceratopsidae). Zoosystematica Rossica 16(2): 292-292. Zoological Institute of the Russian Academy of Sciences. doi:10.31610/zsr/2007.16.2.292

    Single-page note proposing Nedoceratops as a replacement (nomen novum) for the preoccupied Diceratops Lull, 1905; type species Nedoceratops hatcheri (Lull, 1905).

    ukrainsky2007a
  4. Farke, A. A. (2011). Anatomy and Taxonomic Status of the Chasmosaurine Ceratopsid Nedoceratops hatcheri from the Upper Cretaceous Lance Formation of Wyoming, U.S.A. PLOS ONE 6(1): e16196. doi:10.1371/journal.pone.0016196

    Pro-validity reassessment of Nedoceratops hatcheri (USNM 2412), diagnosing the genus by an undifferentiated nasal horncore, near-vertical postorbital horncores, and small parietal fenestrae.

    farke2011b
  5. Mateus, O. (2008). Two ornithischian dinosaurs renamed: Microceratops Bohlin 1953 and Diceratops Lull 1905. Journal of Paleontology 82(2): 423-423. Cambridge University Press (CUP). doi:10.1666/07-069.1

    Independent replacement-name proposal coining Diceratus for Diceratops Lull, 1905; Mateus was unaware of Ukrainsky's earlier Nedoceratops, making Diceratus a junior objective synonym.

    mateus2008a
  6. Olshevsky, G. (1991). A revision of the parainfraclass Archosauria Cope, 1869, excluding the advanced Crocodylia. Mesozoic Meanderings 2: 1-196.

    Treats Diceratops as a valid genus distinct from Triceratops, following Forster's 1990 SVP work; predates the recognition of the Diceratops preoccupation and the Ukrainsky (2007) replacement.

    olshevsky1991a
  7. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Ornithischians. Princeton University Press.

    Source of the body length estimate, and the appearance features.

    jones2026a
  8. Scannella, J.; Horner, J. R. (2010). Torosaurus Marsh, 1891, is Triceratops Marsh, 1889 (Ceratopsidae: Chasmosaurinae): synonymy through ontogeny. Journal of Vertebrate Paleontology 30(4): 1157-1168. doi:10.1080/02724634.2010.483632

    Treated Nedoceratops as an ontogenetic morph within Triceratops.

    scannella2010a
  9. Scannella, J. B.; Horner, J. R. (2011). 'Nedoceratops': an example of a transitional morphology. PLoS ONE 6(12): e28705. doi:10.1371/journal.pone.0028705

    Treated USNM 2412 (Nedoceratops) as an ontogenetic Triceratops morph within the Torosaurus-Triceratops synonymy argument.

    scannella2011a
  10. Maiorino, L.; Farke, A. A.; Kotsakis, T.; Piras, P. (2013). Is Torosaurus Triceratops? Geometric morphometric evidence of Late Maastrichtian ceratopsid dinosaurs. PLoS ONE 8(11): e81608. Public Library of Science (PLoS). doi:10.1371/journal.pone.0081608

    Morphometric study with equivocal results for Nedoceratops — squamosal and frill fall within Triceratops morphospace, though overall skull shape is ambiguous.

    maiorino2013a