{
  "title": "Primary-source spot review: ceratopsid overlaps and Hell Creek",
  "reviewDate": "2026-10-10",
  "scope": "Bounded primary-source validation supplements all-parent PBDB collection screen; no exhaustive range or absence certification.",
  "coverage": {
    "chasmosaurinePoolSize": 16,
    "chasmosaurineMembersWithPositiveFormationAnchor": 16,
    "chasmosaurineCovered": [
      "Agujaceratops",
      "Anchiceratops",
      "Arrhinoceratops",
      "Bisticeratops",
      "Bravoceratops",
      "Chasmosaurus",
      "Coahuilaceratops",
      "Judiceratops",
      "Kosmoceratops",
      "Navajoceratops",
      "Pentaceratops",
      "Sierraceratops",
      "Spiclypeus",
      "Terminocavus",
      "Utahceratops",
      "Vagaceratops"
    ],
    "otherReviewedContexts": [
      "Centrosaurinae",
      "Centrosaurini",
      "Nasutoceratopsini",
      "Triceratopsini",
      "Lambeosaurinae",
      "Hell Creek tyrannosauroids"
    ],
    "notFullyReviewed": [
      "Menefeeceratops original source",
      "Xenoceratops original source",
      "Crittendenceratops original source",
      "Remaining Lambeosaurinae Asian genus occurrences",
      "Tyrannosauroidea18 all-occurrence ranges"
    ]
  },
  "positiveOverlaps": [
    {
      "genera": [
        "Utahceratops",
        "Kosmoceratops"
      ],
      "country": "US",
      "rank": "formation",
      "name": "Kaiparowits",
      "certainty": "reported",
      "source": {
        "title": "Sampson et al. (2010), New Horned Dinosaurs from Utah Provide Evidence for Intracontinental Dinosaur Endemism",
        "url": "https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0012292",
        "doi": "10.1371/journal.pone.0012292",
        "access": "Full article reviewed"
      },
      "note": "Both type and referred specimens span overlapping lower/middle units. A Kaiparowits clue retains both."
    },
    {
      "genera": [
        "Vagaceratops"
      ],
      "country": "CA",
      "rank": "formation",
      "name": "Dinosaur Park",
      "certainty": "reported",
      "source": {
        "title": "Sampson et al. (2010), New Horned Dinosaurs from Utah Provide Evidence for Intracontinental Dinosaur Endemism",
        "url": "https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0012292",
        "doi": "10.1371/journal.pone.0012292",
        "access": "Full article reviewed"
      },
      "note": "Type and assigned specimens in upper lithofacies."
    },
    {
      "genera": [
        "Chasmosaurus"
      ],
      "country": "CA",
      "rank": "formation",
      "name": "Dinosaur Park",
      "certainty": "reported",
      "source": {
        "title": "Campbell et al. (2016), A Re-Evaluation of the Chasmosaurine Ceratopsid Genus Chasmosaurus",
        "url": "https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0145805",
        "doi": "10.1371/journal.pone.0145805",
        "access": "Full article reviewed"
      },
      "note": "Genus confirmed; C.russelli holotype classification subsequently revised2026."
    },
    {
      "genera": [
        "Anchiceratops",
        "Arrhinoceratops"
      ],
      "country": "CA",
      "rank": "formation",
      "name": "Horseshoe Canyon",
      "certainty": "reported",
      "source": {
        "title": "Fowler and Freedman Fowler (2020), Transitional evolutionary forms in chasmosaurine ceratopsid dinosaurs",
        "url": "https://peerj.com/articles/9251/",
        "doi": "10.7717/peerj.9251",
        "access": "Publisher/PMC indexed full-text passages; publisher access blocked"
      },
      "note": "Both documented in Horsethief/Morrin members; neither can be eliminated by the other having a different type quarry."
    },
    {
      "genera": [
        "Agujaceratops"
      ],
      "country": "US",
      "rank": "formation",
      "name": "Aguja",
      "certainty": "reported",
      "source": {
        "title": "Lehman et al. (2017), New specimens from the Aguja Formation and a revision of Agujaceratops",
        "url": "https://www.tandfonline.com/doi/abs/10.1080/14772019.2016.1210683",
        "doi": "10.1080/14772019.2016.1210683",
        "access": "Publisher abstract"
      },
      "note": "Both named species in the Aguja Formation; not evidence the genus is absent elsewhere."
    },
    {
      "genera": [
        "Bisticeratops"
      ],
      "country": "US",
      "rank": "formation",
      "name": "Kirtland",
      "certainty": "reported",
      "source": {
        "title": "Dalman et al. (2022), A new chasmosaurine ceratopsid from the Farmington Member of the Kirtland Formation",
        "url": "https://www.researchgate.net/publication/362680358_A_new_chasmosaurine_ceratopsid_from_the_Upper_Cretaceous_Campanian_Farmington_Member_of_the_Kirtland_Formation_New_Mexico",
        "access": "Original article indexed abstract and official New Mexico Museum announcement"
      },
      "note": "Skull from Farmington Member."
    },
    {
      "genera": [
        "Bravoceratops"
      ],
      "country": "US",
      "rank": "formation",
      "name": "Javelina",
      "certainty": "reported",
      "source": {
        "title": "Wick and Lehman (2013), A new ceratopsian dinosaur from the Javelina Formation",
        "url": "https://pubmed.ncbi.nlm.nih.gov/23728202/",
        "doi": "10.1007/s00114-013-1063-0",
        "access": "Indexed original article abstract"
      },
      "note": "Lowermost Javelina type material; diagnostic validity disputed in Fowler2020."
    },
    {
      "genera": [
        "Coahuilaceratops"
      ],
      "country": "MX",
      "rank": "formation",
      "name": "Cerro Huerta",
      "certainty": "reported",
      "source": {
        "title": "Barrera Guevara et al. (2024), Stratigraphic Reassessment of Coahuilaceratops magnacuerna",
        "url": "https://www.mdpi.com/1424-2818/16/7/390",
        "doi": "10.3390/d16070390",
        "access": "Original article PDF reviewed through preserved dinodata mirror"
      },
      "note": "Type quarry reassigned from Cerro del Pueblo after measured-section/host-rock review. Preserve old attribution as revision flag, not another independent occurrence."
    },
    {
      "genera": [
        "Judiceratops"
      ],
      "country": "US",
      "rank": "formation",
      "name": "Judith River",
      "certainty": "reported",
      "source": {
        "title": "Longrich (2013), Judiceratops tigris from the Middle Campanian Judith River Formation",
        "url": "https://researchportal.bath.ac.uk/en/publications/judiceratops-tigris-a-new-horned-dinosaur-from-the-middle-campani",
        "doi": "10.3374/014.054.0103",
        "access": "Author institution publication abstract"
      },
      "note": "Middle Campanian specimen; exact within-formation horizon not securely established."
    },
    {
      "genera": [
        "Spiclypeus"
      ],
      "country": "US",
      "rank": "formation",
      "name": "Judith River",
      "certainty": "reported",
      "source": {
        "title": "Mallon et al. (2016), Spiclypeus shipporum gen. et sp. nov.",
        "url": "https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0154218",
        "doi": "10.1371/journal.pone.0154218",
        "access": "Full article reviewed"
      },
      "note": "Lower Coal Ridge Member type specimenCMN57081; geographic overlap at formation scale with Judiceratops despite different sections."
    },
    {
      "genera": [
        "Navajoceratops",
        "Terminocavus"
      ],
      "country": "US",
      "rank": "formation",
      "name": "Kirtland",
      "certainty": "reported",
      "source": {
        "title": "Fowler and Freedman Fowler (2020), Transitional evolutionary forms in chasmosaurine ceratopsid dinosaurs",
        "url": "https://peerj.com/articles/9251/",
        "doi": "10.7717/peerj.9251",
        "access": "Publisher/PMC indexed full-text passages; publisher access blocked"
      },
      "note": "Both type specimens from Hunter Wash Member; lower/middle member differences do not split a formation-level clue."
    },
    {
      "genera": [
        "Pentaceratops"
      ],
      "country": "US",
      "rank": "formation",
      "name": "Fruitland",
      "certainty": "reported",
      "source": {
        "title": "Fowler and Freedman Fowler (2020), Transitional evolutionary forms in chasmosaurine ceratopsid dinosaurs",
        "url": "https://peerj.com/articles/9251/",
        "doi": "10.7717/peerj.9251",
        "access": "Publisher/PMC indexed full-text passages; publisher access blocked"
      },
      "note": "Type species AMNH6325 Fruitland; older broad Kirtland referrals require specimen review."
    },
    {
      "genera": [
        "Sierraceratops"
      ],
      "country": "US",
      "rank": "formation",
      "name": "Hall Lake",
      "certainty": "reported",
      "source": {
        "title": "Dalman et al. (2022), Sierraceratops turneri from the Hall Lake Formation",
        "url": "https://www.sciencedirect.com/science/article/pii/S0195667121002822",
        "doi": "10.1016/j.cretres.2021.105034",
        "access": "Publisher abstract"
      },
      "note": "Original description establishes formation; specimens historically referred to Torosaurus should not duplicate genera as if independent fossils."
    },
    {
      "genera": [
        "Diabloceratops",
        "Machairoceratops"
      ],
      "country": "US",
      "rank": "formation",
      "name": "Wahweap",
      "certainty": "reported",
      "source": {
        "title": "Lund et al. (2016), Machairoceratops cronusi from the Wahweap Formation",
        "url": "https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0154403",
        "doi": "10.1371/journal.pone.0154403",
        "access": "Full article reviewed"
      },
      "note": "Lower/middle versus upper units; formation clue retains both."
    },
    {
      "genera": [
        "Wendiceratops"
      ],
      "country": "CA",
      "rank": "formation",
      "name": "Oldman",
      "certainty": "reported",
      "source": {
        "title": "Evans and Ryan (2015), Cranial Anatomy of Wendiceratops pinhornensis",
        "url": "https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0130007",
        "doi": "10.1371/journal.pone.0130007",
        "access": "Publisher indexed full-text passages"
      },
      "note": "Known bonebed; lower Oldman."
    },
    {
      "genera": [
        "Stellasaurus",
        "Rubeosaurus"
      ],
      "country": "US",
      "rank": "formation",
      "name": "Two Medicine",
      "certainty": "reported",
      "source": {
        "title": "Wilson et al. (2020), A new transitional centrosaurine from Two Medicine Formation",
        "url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC7211873/",
        "doi": "10.1098/rsos.200284",
        "access": "Indexed original full-text passages"
      },
      "note": "Separate specimens within formation; one old Rubeosaurus referral reassigned to Stellasaurus. Taxonomic debate should not become negative evidence."
    },
    {
      "genera": [
        "Coronosaurus",
        "Centrosaurus"
      ],
      "country": "CA",
      "rank": "formation",
      "name": "Oldman",
      "certainty": "reported",
      "source": {
        "title": "Wilson et al. (2020), A new transitional centrosaurine from Two Medicine Formation",
        "url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC7211873/",
        "doi": "10.1098/rsos.200284",
        "access": "Indexed original full-text passages"
      },
      "note": "Source reviews middle Oldman Coronosaurus and upper Oldman Centrosaurus. Different levels preserve formation overlap."
    },
    {
      "genera": [
        "Centrosaurus",
        "Styracosaurus"
      ],
      "country": "CA",
      "rank": "formation",
      "name": "Dinosaur Park",
      "certainty": "reported",
      "source": {
        "title": "Wilson et al. (2020), A new transitional centrosaurine from Two Medicine Formation",
        "url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC7211873/",
        "doi": "10.1098/rsos.200284",
        "access": "Indexed original full-text passages"
      },
      "note": "Both represented at formation level; faunal-zone distinctions do not erase wider formation overlap."
    },
    {
      "genera": [
        "Spinops"
      ],
      "country": "CA",
      "rank": "formation",
      "name": "Oldman",
      "certainty": "uncertain",
      "source": {
        "title": "Farke et al. (2011), A new centrosaurine from the Late Cretaceous of Alberta",
        "url": "https://app.pan.pl/article/item/app20100121.html",
        "doi": "10.4202/app.2010.0121",
        "access": "Original publisher abstract"
      },
      "note": "Quarry could be upper Oldman OR lower Dinosaur Park. Preserve as possible in either, not two confirmed independent occurrences."
    },
    {
      "genera": [
        "Spinops"
      ],
      "country": "CA",
      "rank": "formation",
      "name": "Dinosaur Park",
      "certainty": "uncertain",
      "source": {
        "title": "Farke et al. (2011), A new centrosaurine from the Late Cretaceous of Alberta",
        "url": "https://app.pan.pl/article/item/app20100121.html",
        "doi": "10.4202/app.2010.0121",
        "access": "Original publisher abstract"
      },
      "note": "Same ambiguous quarry as Oldman record; retain for either clue."
    },
    {
      "genera": [
        "Furcatoceratops"
      ],
      "country": "US",
      "rank": "formation",
      "name": "Judith River",
      "certainty": "reported",
      "source": {
        "title": "Ishikawa et al. (2023), Furcatoceratops elucidans from Judith River Formation",
        "url": "https://www.sciencedirect.com/science/article/pii/S019566712300188X",
        "doi": "10.1016/j.cretres.2023.105660",
        "access": "Publisher abstract"
      },
      "note": "Original description establishes formation."
    },
    {
      "genera": [
        "Avaceratops"
      ],
      "country": "US",
      "rank": "formation",
      "name": "Judith River",
      "certainty": "reported",
      "source": {
        "title": "Mallon et al. (2016), Spiclypeus shipporum gen. et sp. nov.",
        "url": "https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0154218",
        "doi": "10.1371/journal.pone.0154218",
        "access": "Full article reviewed"
      },
      "note": "Type skeleton Careless Creek Quarry; member/age less secure than formation identification."
    },
    {
      "genera": [
        "Yehuecauhceratops"
      ],
      "country": "MX",
      "rank": "formation",
      "name": "Aguja",
      "certainty": "reported",
      "source": {
        "title": "Rivera-Sylva et al. (2017), Mexican ceratopsids: considerations on diversity and biogeography",
        "url": "https://www.sciencedirect.com/science/article/abs/pii/S0895981116302917",
        "doi": "10.1016/j.jsames.2017.01.008",
        "access": "Publisher abstract"
      },
      "note": "Original description establishes formation."
    },
    {
      "genera": [
        "Nasutoceratops"
      ],
      "country": "US",
      "rank": "formation",
      "name": "Kaiparowits",
      "certainty": "reported",
      "source": {
        "title": "Lund et al. (2016), Machairoceratops cronusi from the Wahweap Formation",
        "url": "https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0154403",
        "doi": "10.1371/journal.pone.0154403",
        "access": "Full article reviewed"
      },
      "note": "Original Machairoceratops comparative geological context names Nasutoceratops from overlying Kaiparowits."
    },
    {
      "genera": [
        "Torosaurus"
      ],
      "country": "US",
      "rank": "formation",
      "name": "Hell Creek",
      "certainty": "reported",
      "source": {
        "title": "McDonald et al. (2016), A New Specimen of Torosaurus latus from Hell Creek",
        "url": "https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0151453",
        "doi": "10.1371/journal.pone.0151453",
        "access": "Full article reviewed"
      },
      "note": "ESU2009-6 Montana plus other cited Montana/SouthDakota specimens; type Lance locality must not exclude HellCreek."
    },
    {
      "genera": [
        "Torosaurus"
      ],
      "country": "US",
      "rank": "formation",
      "name": "Lance",
      "certainty": "reported",
      "source": {
        "title": "McDonald et al. (2016), A New Specimen of Torosaurus latus from Hell Creek",
        "url": "https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0151453",
        "doi": "10.1371/journal.pone.0151453",
        "access": "Full article reviewed"
      },
      "note": "HolotypeYPM1830 andYPM1831 Wyoming."
    },
    {
      "genera": [
        "Triceratops",
        "Torosaurus"
      ],
      "country": "US",
      "rank": "formation",
      "name": "Hell Creek",
      "certainty": "reported",
      "source": {
        "title": "Longrich and Field (2012), Torosaurus Is Not Triceratops",
        "url": "https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0032623",
        "doi": "10.1371/journal.pone.0032623",
        "access": "Full article geographic section reviewed"
      },
      "note": "Both genera overlap; broad formation statement cannot distinguish these genera."
    },
    {
      "genera": [
        "Triceratops",
        "Torosaurus"
      ],
      "country": "US",
      "rank": "formation",
      "name": "Lance",
      "certainty": "reported",
      "source": {
        "title": "Longrich and Field (2012), Torosaurus Is Not Triceratops",
        "url": "https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0032623",
        "doi": "10.1371/journal.pone.0032623",
        "access": "Full article geographic section reviewed"
      },
      "note": "Geographic-distribution comparison includes Wyoming Lance overlap; cannot assign the two to exclusive HellCreek/Lance buckets."
    },
    {
      "genera": [
        "Tyrannosaurus"
      ],
      "country": "US",
      "rank": "formation",
      "name": "Hell Creek",
      "certainty": "reported",
      "source": {
        "title": "American Museum of Natural History, 7 Questions About Tyrannosaurus rex",
        "url": "https://www.amnh.org/dinosaurs/tyrannosaurus-rex",
        "access": "Museum original collection history"
      },
      "note": "Museum type history:1902 Montana partial skeleton. Genus also has other localities; type narrative not complete range."
    },
    {
      "genera": [
        "Nanotyrannus",
        "Tyrannosaurus"
      ],
      "country": "US",
      "rank": "formation",
      "name": "Hell Creek",
      "certainty": "reported",
      "source": {
        "title": "Zanno and Napoli (2025), Nanotyrannus and Tyrannosaurus coexisted at the close of the Cretaceous",
        "url": "https://www.nature.com/articles/s41586-025-09801-6",
        "doi": "10.1038/s41586-025-09801-6",
        "access": "Publisher indexed abstract; has publisher correction10.1038/s41586-026-10185-4"
      },
      "note": "NCSM40000 HellCreek; contemporary genera according to2025 systematic interpretation. PBDB inclusion/classification remains source-policy controlled."
    },
    {
      "genera": [
        "Amurosaurus"
      ],
      "country": "RU",
      "rank": "formation",
      "name": "Udurchukan",
      "certainty": "reported",
      "source": {
        "title": "Godefroit et al. (2004), The lambeosaurine dinosaur Amurosaurus riabinini from Maastrichtian Far Eastern Russia",
        "url": "https://app.pan.pl/archive/published/app49/app49-585.pdf",
        "access": "Original publisher indexed article"
      },
      "note": "Blagoveshchensk specimens. Do not equate formation with exact Kundur quarry."
    },
    {
      "genera": [
        "Olorotitan"
      ],
      "country": "RU",
      "rank": "formation",
      "name": "Udurchukan",
      "certainty": "reported",
      "source": {
        "title": "Godefroit et al. (2012), Osteology and relationships of Olorotitan arharensis",
        "url": "https://app.pan.pl/article/item/app20110051.html",
        "doi": "10.4202/app.2011.0051",
        "access": "Original publisher abstract"
      },
      "note": "Holotype from Kundur; same formation as classic Amurosaurus Blagoveshchensk records."
    },
    {
      "genera": [
        "Titanoceratops"
      ],
      "country": "US",
      "rank": "formation",
      "name": "Fruitland",
      "certainty": "uncertain",
      "source": {
        "title": "Longrich (2011), Titanoceratops ouranos, a giant horned dinosaur from the late Campanian of New Mexico",
        "url": "https://www.sciencedirect.com/science/article/pii/S0195667110001205",
        "doi": "10.1016/j.cretres.2010.12.007",
        "access": "Publisher indexed geographic section"
      },
      "note": "Original description:upper Fruitland OR lower Kirtland. One uncertain fossil provenance, not two independent occurrences."
    },
    {
      "genera": [
        "Titanoceratops"
      ],
      "country": "US",
      "rank": "formation",
      "name": "Kirtland",
      "certainty": "uncertain",
      "source": {
        "title": "Longrich (2011), Titanoceratops ouranos, a giant horned dinosaur from the late Campanian of New Mexico",
        "url": "https://www.sciencedirect.com/science/article/pii/S0195667110001205",
        "doi": "10.1016/j.cretres.2010.12.007",
        "access": "Publisher indexed geographic section"
      },
      "note": "Retain as possible due uncertain formation attribution."
    }
  ],
  "revisionFlags": [
    {
      "genera": [
        "Kosmoceratops",
        "Chasmosaurus"
      ],
      "issue": "Dinosaur Park CMN8801 identified as Kosmoceratops2014, rejected2016 as Chasmosaurus; possible overlap must remain flagged until occurrence-level adjudication, not mechanically excluded.",
      "source": {
        "title": "Campbell et al. (2016), A Re-Evaluation of the Chasmosaurine Ceratopsid Genus Chasmosaurus",
        "url": "https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0145805",
        "doi": "10.1371/journal.pone.0145805",
        "access": "Full article reviewed"
      }
    },
    {
      "genera": [
        "Pentaceratops",
        "Spiclypeus"
      ],
      "issue": "Alberta P.aquilonius material from Lethbridge Coal Zone reassessed as nomen dubium; paratype possibly Spiclypeus. This is disputed identification, not verified genus absence.",
      "source": {
        "title": "Mallon et al. (2016), Spiclypeus shipporum gen. et sp. nov.",
        "url": "https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0154218",
        "doi": "10.1371/journal.pone.0154218",
        "access": "Full article reviewed"
      }
    },
    {
      "genera": [
        "Vagaceratops",
        "Chasmosaurus"
      ],
      "issue": "2019 analysis returns V.irvinensis to Chasmosaurus. Follow frozen PBDB genus policy until deliberate source update; do not double-count one specimen as two independent supporting occurrences.",
      "source": {
        "title": "Campbell et al. (2019), Temporal range extension and evolution of the chasmosaurine ceratopsid Vagaceratops irvinensis",
        "url": "https://journals.library.ualberta.ca/vamp/index.php/VAMP/article/view/29356",
        "doi": "10.18435/vamp29356",
        "access": "Original article PDF reviewed through preserved distantreader mirror"
      }
    },
    {
      "genera": [
        "Chasmosaurus",
        "Cryptarcus"
      ],
      "issue": "2026 revision establishes Cryptarcus for C.russelli holotypeCMNFV8800 and referred material. Fresh primary evidence can expose stale occurrence assignments even in recent PBDB snapshot. Flag; do not silently rewrite roster.",
      "source": {
        "title": "Holmes et al. (2026), New information on the holotype of Chasmosaurus russelli necessitates the establishment of a new genus",
        "url": "https://doi.org/10.1139/cjes-2025-0031",
        "doi": "10.1139/cjes-2025-0031",
        "access": "Original article PDF reviewed through preserved dinosaurier-info mirror"
      }
    },
    {
      "genera": [
        "Bravoceratops"
      ],
      "issue": "Fowler2020 questions diagnostic validity/reconstruction; roster inclusion follows PBDB but hidden-answer/locality approval still requires reviewed material.",
      "source": {
        "title": "Fowler and Freedman Fowler (2020), Transitional evolutionary forms in chasmosaurine ceratopsid dinosaurs",
        "url": "https://peerj.com/articles/9251/",
        "doi": "10.7717/peerj.9251",
        "access": "Publisher/PMC indexed full-text passages; publisher access blocked"
      }
    },
    {
      "genera": [
        "Torosaurus",
        "Triceratops"
      ],
      "issue": "Competing ontogenetic synonymy hypotheses do not remove geographic overlap. Source policy determines names; fossil provenance remains shared.",
      "source": {
        "title": "McDonald et al. (2016), A New Specimen of Torosaurus latus from Hell Creek",
        "url": "https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0151453",
        "doi": "10.1371/journal.pone.0151453",
        "access": "Full article reviewed"
      }
    }
  ],
  "interpretation": [
    "All positive memberships are additive and nonexclusive.",
    "An uncertain identification or uncertain formation retains candidate plausibility; it does not justify a definite clue for that hidden answer.",
    "A type/first-discovered locality may select a narrative anchor, but comparison uses all documented memberships for every candidate.",
    "Formation, member, county and digsite are different geographic/stratigraphic resolutions.",
    "No absence from this research list proves absence from a locality. Lower-bound overlaps are not final remaining-answer counts.",
    "Data-source updates and genus-level referrals need curator review before changes enter gameplay."
  ],
  "sources": {
    "sampson2010": {
      "title": "Sampson et al. (2010), New Horned Dinosaurs from Utah Provide Evidence for Intracontinental Dinosaur Endemism",
      "url": "https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0012292",
      "doi": "10.1371/journal.pone.0012292",
      "access": "Full article reviewed"
    },
    "campbell2016": {
      "title": "Campbell et al. (2016), A Re-Evaluation of the Chasmosaurine Ceratopsid Genus Chasmosaurus",
      "url": "https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0145805",
      "doi": "10.1371/journal.pone.0145805",
      "access": "Full article reviewed"
    },
    "campbell2019": {
      "title": "Campbell et al. (2019), Temporal range extension and evolution of the chasmosaurine ceratopsid Vagaceratops irvinensis",
      "url": "https://journals.library.ualberta.ca/vamp/index.php/VAMP/article/view/29356",
      "doi": "10.18435/vamp29356",
      "access": "Original article PDF reviewed through preserved distantreader mirror"
    },
    "holmes2026": {
      "title": "Holmes et al. (2026), New information on the holotype of Chasmosaurus russelli necessitates the establishment of a new genus",
      "url": "https://doi.org/10.1139/cjes-2025-0031",
      "doi": "10.1139/cjes-2025-0031",
      "access": "Original article PDF reviewed through preserved dinosaurier-info mirror"
    },
    "coahuila2024": {
      "title": "Barrera Guevara et al. (2024), Stratigraphic Reassessment of Coahuilaceratops magnacuerna",
      "url": "https://www.mdpi.com/1424-2818/16/7/390",
      "doi": "10.3390/d16070390",
      "access": "Original article PDF reviewed through preserved dinodata mirror"
    },
    "fowler2020": {
      "title": "Fowler and Freedman Fowler (2020), Transitional evolutionary forms in chasmosaurine ceratopsid dinosaurs",
      "url": "https://peerj.com/articles/9251/",
      "doi": "10.7717/peerj.9251",
      "access": "Publisher/PMC indexed full-text passages; publisher access blocked"
    },
    "mallon2016": {
      "title": "Mallon et al. (2016), Spiclypeus shipporum gen. et sp. nov.",
      "url": "https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0154218",
      "doi": "10.1371/journal.pone.0154218",
      "access": "Full article reviewed"
    },
    "judiceratops2013": {
      "title": "Longrich (2013), Judiceratops tigris from the Middle Campanian Judith River Formation",
      "url": "https://researchportal.bath.ac.uk/en/publications/judiceratops-tigris-a-new-horned-dinosaur-from-the-middle-campani",
      "doi": "10.3374/014.054.0103",
      "access": "Author institution publication abstract"
    },
    "sierraceratops2022": {
      "title": "Dalman et al. (2022), Sierraceratops turneri from the Hall Lake Formation",
      "url": "https://www.sciencedirect.com/science/article/pii/S0195667121002822",
      "doi": "10.1016/j.cretres.2021.105034",
      "access": "Publisher abstract"
    },
    "bravoceratops2013": {
      "title": "Wick and Lehman (2013), A new ceratopsian dinosaur from the Javelina Formation",
      "url": "https://pubmed.ncbi.nlm.nih.gov/23728202/",
      "doi": "10.1007/s00114-013-1063-0",
      "access": "Indexed original article abstract"
    },
    "agujaceratops2017": {
      "title": "Lehman et al. (2017), New specimens from the Aguja Formation and a revision of Agujaceratops",
      "url": "https://www.tandfonline.com/doi/abs/10.1080/14772019.2016.1210683",
      "doi": "10.1080/14772019.2016.1210683",
      "access": "Publisher abstract"
    },
    "bisticeratops2022": {
      "title": "Dalman et al. (2022), A new chasmosaurine ceratopsid from the Farmington Member of the Kirtland Formation",
      "url": "https://www.researchgate.net/publication/362680358_A_new_chasmosaurine_ceratopsid_from_the_Upper_Cretaceous_Campanian_Farmington_Member_of_the_Kirtland_Formation_New_Mexico",
      "access": "Original article indexed abstract and official New Mexico Museum announcement"
    },
    "anchiceratops2011": {
      "title": "Mallon et al. (2011), Variation in the skull of Anchiceratops",
      "url": "https://www.tandfonline.com/doi/abs/10.1080/02724634.2011.601484",
      "doi": "10.1080/02724634.2011.601484",
      "access": "Publisher abstract"
    },
    "arrhinoceratops2014": {
      "title": "Mallon et al. (2014), New information on Arrhinoceratops brachyops",
      "url": "https://doi.org/10.1139/cjes-2014-0028",
      "doi": "10.1139/cjes-2014-0028",
      "access": "Author-uploaded original abstract, referenced in Fowler2020"
    },
    "lund2016": {
      "title": "Lund et al. (2016), Machairoceratops cronusi from the Wahweap Formation",
      "url": "https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0154403",
      "doi": "10.1371/journal.pone.0154403",
      "access": "Full article reviewed"
    },
    "spinops2011": {
      "title": "Farke et al. (2011), A new centrosaurine from the Late Cretaceous of Alberta",
      "url": "https://app.pan.pl/article/item/app20100121.html",
      "doi": "10.4202/app.2010.0121",
      "access": "Original publisher abstract"
    },
    "stellasaurus2020": {
      "title": "Wilson et al. (2020), A new transitional centrosaurine from Two Medicine Formation",
      "url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC7211873/",
      "doi": "10.1098/rsos.200284",
      "access": "Indexed original full-text passages"
    },
    "wendiceratops2015": {
      "title": "Evans and Ryan (2015), Cranial Anatomy of Wendiceratops pinhornensis",
      "url": "https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0130007",
      "doi": "10.1371/journal.pone.0130007",
      "access": "Publisher indexed full-text passages"
    },
    "furcatoceratops2023": {
      "title": "Ishikawa et al. (2023), Furcatoceratops elucidans from Judith River Formation",
      "url": "https://www.sciencedirect.com/science/article/pii/S019566712300188X",
      "doi": "10.1016/j.cretres.2023.105660",
      "access": "Publisher abstract"
    },
    "yehuecauhceratops2017": {
      "title": "Rivera-Sylva et al. (2017), Mexican ceratopsids: considerations on diversity and biogeography",
      "url": "https://www.sciencedirect.com/science/article/abs/pii/S0895981116302917",
      "doi": "10.1016/j.jsames.2017.01.008",
      "access": "Publisher abstract"
    },
    "torosaurus2016": {
      "title": "McDonald et al. (2016), A New Specimen of Torosaurus latus from Hell Creek",
      "url": "https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0151453",
      "doi": "10.1371/journal.pone.0151453",
      "access": "Full article reviewed"
    },
    "longrichfield2012": {
      "title": "Longrich and Field (2012), Torosaurus Is Not Triceratops",
      "url": "https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0032623",
      "doi": "10.1371/journal.pone.0032623",
      "access": "Full article geographic section reviewed"
    },
    "amnhTyrannosaurus": {
      "title": "American Museum of Natural History, 7 Questions About Tyrannosaurus rex",
      "url": "https://www.amnh.org/dinosaurs/tyrannosaurus-rex",
      "access": "Museum original collection history"
    },
    "nanotyrannus2025": {
      "title": "Zanno and Napoli (2025), Nanotyrannus and Tyrannosaurus coexisted at the close of the Cretaceous",
      "url": "https://www.nature.com/articles/s41586-025-09801-6",
      "doi": "10.1038/s41586-025-09801-6",
      "access": "Publisher indexed abstract; has publisher correction10.1038/s41586-026-10185-4"
    },
    "olorotitan2012": {
      "title": "Godefroit et al. (2012), Osteology and relationships of Olorotitan arharensis",
      "url": "https://app.pan.pl/article/item/app20110051.html",
      "doi": "10.4202/app.2011.0051",
      "access": "Original publisher abstract"
    },
    "amurosaurus2004": {
      "title": "Godefroit et al. (2004), The lambeosaurine dinosaur Amurosaurus riabinini from Maastrichtian Far Eastern Russia",
      "url": "https://app.pan.pl/archive/published/app49/app49-585.pdf",
      "access": "Original publisher indexed article"
    },
    "titanoceratops2011": {
      "title": "Longrich (2011), Titanoceratops ouranos, a giant horned dinosaur from the late Campanian of New Mexico",
      "url": "https://www.sciencedirect.com/science/article/pii/S0195667110001205",
      "doi": "10.1016/j.cretres.2010.12.007",
      "access": "Publisher indexed geographic section"
    }
  }
}